SETTING THE DIRECTORY AND READING THE DATA

setwd("C:/Users/Bagga/Desktop/Internship 2018/Week 4, Day 1")
salary <- read.csv("C:/Users/Bagga/Desktop/Internship 2018/Week 4, Day 1/MBA Starting Salaries Data.csv")
salary
##     age sex gmat_tot gmat_qpc gmat_vpc gmat_tpc s_avg f_avg quarter
## 1    23   2      620       77       87       87  3.40  3.00       1
## 2    24   1      610       90       71       87  3.50  4.00       1
## 3    24   1      670       99       78       95  3.30  3.25       1
## 4    24   1      570       56       81       75  3.30  2.67       1
## 5    24   2      710       93       98       98  3.60  3.75       1
## 6    24   1      640       82       89       91  3.90  3.75       1
## 7    25   1      610       89       74       87  3.40  3.50       1
## 8    25   2      650       88       89       92  3.30  3.75       1
## 9    25   1      630       79       91       89  3.30  3.25       1
## 10   25   1      680       99       81       96  3.45  3.67       1
## 11   26   1      740       99       98       99  3.56  4.00       1
## 12   26   2      610       75       87       86  3.40  3.75       1
## 13   26   1      710       95       95       98  3.50  3.50       1
## 14   26   1      720       97       97       99  3.40  4.00       1
## 15   26   2      660       84       93       94  3.30  3.25       1
## 16   26   2      640       67       98       92  4.00  4.00       1
## 17   27   2      660       71       99       95  3.50  4.00       1
## 18   27   1      600       77       78       84  3.30  3.50       1
## 19   27   1      630       79       89       89  3.50  4.00       1
## 20   27   1      600       91       58       83  3.40  3.25       1
## 21   27   2      570       65       82       77  3.30  3.25       1
## 22   27   1      740       99       96       99  3.50  3.50       1
## 23   27   1      750       99       98       99  3.40  3.50       1
## 24   28   2      540       75       50       65  3.60  4.00       1
## 25   29   1      580       56       87       78  3.64  3.33       1
## 26   30   1      620       82       84       87  3.40  2.80       1
## 27   31   2      560       60       78       72  3.30  3.75       1
## 28   32   1      760       99       99       99  3.40  3.00       1
## 29   32   1      640       79       91       91  3.60  3.75       1
## 30   32   1      570       71       71        0  3.50  3.50       1
## 31   34   2      620       75       89       87  3.30  3.00       1
## 32   37   2      560       43       87       72  3.40  3.50       1
## 33   42   2      650       75       98       93  3.38  3.00       1
## 34   48   1      590       84       62       81  3.80  4.00       1
## 35   22   2      660       90       92       94  3.50  3.75       1
## 36   27   2      700       94       98       98  3.30  3.25       1
## 37   25   2      680       87       96       96  3.50  2.67       1
## 38   25   2      650       82       91       93  3.40  3.25       1
## 39   27   1      710       96       96       98  3.30  3.50       1
## 40   28   2      620       52       98       87  3.40  3.75       1
## 41   24   1      670       84       96       95  3.30  3.25       1
## 42   25   2      560       52       81       72  3.30  3.50       1
## 43   25   2      530       50       62       61  3.60  3.67       1
## 44   25   1      650       79       93       93  3.30  3.50       1
## 45   26   2      590       56       89       81  3.30  3.25       1
## 46   23   2      650       93       81       93  3.40  3.00       1
## 47   24   1      560       81       50       71  3.40  3.67       1
## 48   27   1      610       72       84       86  3.30  3.50       1
## 49   25   1      650       95       84       93  3.30  3.00       1
## 50   25   1      550       74       50       68  3.50  3.50       1
## 51   26   1      570       68       74       75  3.80  3.50       1
## 52   26   1      580       79       71       78  3.45  3.50       1
## 53   30   1      600       60       91       83  3.30  3.25       1
## 54   31   1      570       72       71       75  3.60  3.50       1
## 55   30   1      620       60       96       87  3.50  3.00       1
## 56   30   2      680       96       87       96  3.70  3.60       1
## 57   27   1      630       93       75       91  3.30  3.25       1
## 58   25   1      600       82       74       83  3.50  3.25       1
## 59   28   2      640       89       81       91  3.60  3.50       1
## 60   39   1      600       72       81       83  3.60  3.50       1
## 61   27   1      570       95       33       75  3.70  4.00       1
## 62   27   1      710       95       98       98  3.60  3.50       1
## 63   33   1      620       72       89       87  3.50  3.50       1
## 64   27   1      600       67       84       83  3.50  3.00       1
## 65   28   1      700       95       95       98  3.80  4.00       1
## 66   30   1      600       77       81       84  3.50  3.25       1
## 67   30   2      670       87       95       95  3.30  3.25       1
## 68   40   1      630       71       95       91  4.00  0.00       1
## 69   25   1      700       98       93       98  3.60  3.75       1
## 70   22   1      600       95       54       83  3.00  3.00       2
## 71   23   1      640       89       87       92  3.00  3.00       2
## 72   24   1      550       73       63       69  3.10  3.00       2
## 73   24   1      570       82       58       75  3.09  3.50       2
## 74   24   1      620       82       84       87  3.10  3.50       2
## 75   25   2      570       61       81       76  3.00  3.25       2
## 76   25   1      660       94       84       94  3.27  3.75       2
## 77   25   1      680       94       92       97  3.17  3.50       2
## 78   25   1      690       87       98       98  3.00  3.00       2
## 79   25   2      670       99       85       96  3.00  3.25       2
## 80   25   1      690       94       95       98  3.00  2.75       2
## 81   25   2      630       83       89       90  3.00  2.75       2
## 82   25   1      670       99       74       96  3.18  3.25       2
## 83   25   1      680       91       95       97  3.00  3.00       2
## 84   25   1      690       96       89       97  3.00  3.00       2
## 85   25   1      670       97       81       95  3.10  3.25       2
## 86   25   1      580       79       71       78  3.10  2.33       2
## 87   26   1      680       92       93       97  3.00  3.00       2
## 88   26   2      560       64       71       72  3.20  3.25       2
## 89   26   1      560       87       41       72  3.00  3.00       2
## 90   26   1      530       68       54       62  3.09  3.17       2
## 91   27   1      740       99       98       99  3.10  3.50       2
## 92   27   1      720       99       95       99  3.10  3.25       2
## 93   27   1      590       60       87       81  3.00  2.75       2
## 94   27   1      630       87       84       89  3.20  3.00       2
## 95   27   1      560       60       71       72  3.20  3.00       2
## 96   28   2      450       49       22       44  3.10  3.75       2
## 97   28   1      620       81       90       89  3.20  3.00       2
## 98   28   2      610       85       78       86  3.10  3.00       2
## 99   28   1      660       95       85       96  3.10  3.25       2
## 100  29   1      660       94       87       94  3.00  3.00       2
## 101  29   1      580       91       50       80  3.10  2.67       2
## 102  29   1      510       57       50       55  3.27  3.40       2
## 103  29   2      640       90       84       92  3.20  3.00       2
## 104  29   1      610       91       62       86  3.10  3.67       2
## 105  29   1      590       68       84       81  3.10  3.00       2
## 106  29   1      580       79       67       78  3.00  3.25       2
## 107  30   1      680       97       87       96  3.00  3.00       2
## 108  31   1      670       83       98       96  3.20  3.40       2
## 109  32   2      610       64       89       86  3.25  0.00       2
## 110  35   1      540       43       78       65  3.20  3.25       2
## 111  35   1      630       66       95       90  3.08  3.25       2
## 112  36   2      530       48       71       62  3.00  2.50       2
## 113  36   1      650       87       89       93  3.00  3.20       2
## 114  43   1      630       82       87       89  3.10  3.00       2
## 115  26   2      670       87       95       95  3.10  3.33       2
## 116  25   2      620       89       74       87  3.10  3.50       2
## 117  31   1      540       60       62       65  3.10  3.00       2
## 118  25   1      670       95       89       95  3.20  3.50       2
## 119  25   1      610       87       71       86  3.27  3.25       2
## 120  24   1      560       52       81       72  3.20  3.25       2
## 121  24   1      500       78       30       52  3.00  2.75       2
## 122  23   1      590       72       81       81  3.20  3.25       2
## 123  24   1      570       82       58       75  3.20  3.25       2
## 124  26   2      570       93       37       75  3.00  2.75       2
## 125  28   2      580       83       58       79  3.10  3.00       2
## 126  24   2      580       72       71       78  3.00  3.25       2
## 127  31   1      560       68       67       72  3.09  3.00       2
## 128  25   2      620       89       74       87  3.10  3.50       2
## 129  27   1      620       97       63       88  3.20  3.00       2
## 130  28   1      560       75       58       72  3.20  3.25       2
## 131  26   1      680       84       96       96  3.20  3.25       2
## 132  27   1      620       81       87       89  3.00  3.00       2
## 133  34   1      550       72       58       69  3.00  3.00       2
## 134  26   1      600       84       67       83  3.09  3.50       2
## 135  29   1      670       91       93       95  3.10  3.00       2
## 136  24   1      620       84       81       87  3.00  3.25       2
## 137  27   1      630       72       95       89  3.20  3.00       2
## 138  26   1      650       89       87       93  3.20  3.25       2
## 139  24   1      620       88       74       87  3.10  3.00       2
## 140  23   1      720       95       98       99  2.80  2.50       3
## 141  24   2      640       94       78       92  2.90  3.25       3
## 142  24   1      710       96       97       99  2.80  2.75       3
## 143  24   1      670       94       89       96  2.70  3.00       3
## 144  24   2      710       97       97       99  2.80  3.00       3
## 145  24   1      650       89       84       93  2.70  3.25       3
## 146  24   1      600       89       62       83  2.90  3.00       3
## 147  24   2      640       96       71       91  2.70  2.50       3
## 148  25   1      600       89       62       83  2.70  3.25       3
## 149  25   1      630       79       91       89  2.70  2.75       3
## 150  25   1      550       72       58       69  2.90  3.00       3
## 151  25   1      710       99       91       98  2.90  3.25       3
## 152  25   1      660       95       84       94  2.70  3.00       3
## 153  25   1      630       93       71       89  2.90  3.25       3
## 154  25   1      560       79       58       72  2.73  3.17       3
## 155  26   1      670       97       81       96  2.70  2.50       3
## 156  26   1      660       88       93       94  2.90  2.75       3
## 157  26   1      630       83       87       90  2.70  3.00       3
## 158  26   1      640       87       84       91  2.70  3.20       3
## 159  26   1      560       56       81       72  2.80  3.25       3
## 160  26   1      540       52       71       65  2.70  2.75       3
## 161  26   1      600       97       45       83  2.70  3.00       3
## 162  26   2      570       48       89       75  2.82  2.50       3
## 163  26   1      610       82       81       86  2.90  2.75       3
## 164  27   1      650       89       84       93  2.90  3.00       3
## 165  27   2      550       66       63       69  2.90  3.00       3
## 166  27   1      730       95       99       99  2.90  3.33       3
## 167  27   1      610       97       45       86  2.70  2.50       3
## 168  27   2      630       82       89       89  2.70  3.25       3
## 169  27   2      560       61       74       73  2.80  3.25       3
## 170  27   2      620       97       54       87  2.70  2.75       3
## 171  27   1      600       68       87       83  2.90  3.25       3
## 172  27   1      650       79       95       93  2.70  3.25       3
## 173  27   1      560       52       81       72  2.70  2.75       3
## 174  27   1      610       48       98       86  2.70  3.00       3
## 175  27   1      600       77       81       84  2.70  3.00       3
## 176  28   1      460       66       16       37  2.70  2.50       3
## 177  28   1      650       99       63       93  2.90  3.00       3
## 178  28   2      610       64       93       86  2.80  3.25       3
## 179  28   1      500       46       54       52  2.90  2.75       3
## 180  29   1      590       92       58       81  2.80  2.75       3
## 181  29   1      560       57       74       73  2.80  3.00       3
## 182  32   1      550       52       78       71  2.70  2.75       3
## 183  34   1      610       79       81       86  2.80  3.00       3
## 184  34   1      610       82       78       86  2.70  3.00       3
## 185  43   1      480       49       41       45  2.90  3.25       3
## 186  23   2      520       43       67       58  2.90  2.75       3
## 187  27   1      620       87       74       87  2.70  2.75       3
## 188  25   1      580       78       67       80  2.90  3.25       3
## 189  25   1      630       75       93       89  2.70  2.50       3
## 190  25   1      610       89       74       87  2.70  2.75       3
## 191  29   2      560       64       71       72  2.90  3.00       3
## 192  27   1      620       79       87       88  2.90  2.75       3
## 193  28   1      580       72       71       78  2.80  3.00       3
## 194  24   2      670       83       98       96  2.90  3.25       3
## 195  25   2      560       39       91       72  2.90  3.00       3
## 196  25   2      580       72       71       78  2.80  3.25       3
## 197  27   1      680       97       90       97  2.90  2.75       3
## 198  28   1      610       89       67       86  2.70  3.00       3
## 199  29   1      710       93       98       99  2.90  3.25       3
## 200  24   1      710       99       92       99  2.90  3.00       3
## 201  25   2      630       84       87       89  2.80  2.75       3
## 202  24   2      600       89       67       85  2.80  3.00       3
## 203  29   1      660       91       90       95  2.80  3.00       3
## 204  30   1      670       83       97       96  2.80  2.75       3
## 205  24   1      580       89       54       78  2.91  2.83       3
## 206  29   1      680       79       99       96  2.90  3.00       3
## 207  32   1      660       83       95       94  2.90  3.50       3
## 208  28   1      570       56       84       75  2.90  3.00       3
## 209  24   1      680       96       87       97  2.80  2.75       3
## 210  24   1      610       82       81       86  2.50  2.75       4
## 211  24   1      640       93       78       91  2.40  2.50       4
## 212  25   1      600       53       95       84  2.50  3.00       4
## 213  25   1      730       98       96       99  2.40  2.75       4
## 214  25   2      650       87       91       93  2.50  2.50       4
## 215  25   1      640       79       93       91  2.67  0.00       4
## 216  25   1      590       68       81       81  2.60  2.75       4
## 217  25   1      590       97       41       81  2.50  2.75       4
## 218  25   1      700       99       87       98  2.00  2.00       4
## 219  26   1      660       93       87       95  2.60  2.00       4
## 220  26   1      450       28       46       34  2.10  2.00       4
## 221  26   1      560       87       45       72  2.60  3.00       4
## 222  26   1      600       75       78       83  2.20  2.25       4
## 223  26   1      570       82       58       75  2.50  2.75       4
## 224  26   1      590       89       58       81  2.50  2.25       4
## 225  26   2      670       98       81       95  2.60  2.50       4
## 226  27   1      660       97       81       94  2.50  2.50       4
## 227  27   2      560       59       74       73  2.40  2.50       4
## 228  27   1      790       99       99       99  2.40  2.50       4
## 229  27   1      630       93       78       91  2.10  2.50       4
## 230  27   1      580       84       58       78  2.70  2.75       4
## 231  27   1      620       85       85       89  3.30  3.00       4
## 232  27   1      670       89       91       95  3.60  3.25       4
## 233  27   1      580       74       70       78  3.40  3.25       4
## 234  28   1      560       74       67       73  3.60  3.60       4
## 235  28   1      620       93       71       87  2.40  2.75       4
## 236  28   1      710       94       98       99  3.40  3.75       4
## 237  28   1      570       69       71        0  2.30  2.50       4
## 238  29   1      530       35       81       62  3.30  2.75       4
## 239  29   1      690       99       87       97  2.30  2.25       4
## 240  29   1      630       87       84       89  2.90  2.80       4
## 241  29   1      670       91       91       95  3.30  3.25       4
## 242  29   1      630       99       50       89  2.90  3.25       4
## 243  29   2      680       89       96       96  2.80  3.00       4
## 244  30   1      650       88       92       93  3.45  3.83       4
## 245  30   1      550       79       45       69  2.45  2.75       4
## 246  30   2      600       99       46       86  2.80  3.00       4
## 247  30   1      630       82       87       89  3.80  3.50       4
## 248  31   1      580       83       67       79  3.00  3.25       4
## 249  31   1      740       99       98       99  2.20  3.00       4
## 250  31   1      570       75       62       75  2.80  3.00       4
## 251  31   1      640       79       92       92  2.70  2.75       4
## 252  32   1      570       89       41       75  2.60  2.50       4
## 253  32   1      510       79       22       54  2.30  2.25       4
## 254  35   1      570       72       71       75  3.30  4.00       4
## 255  39   2      700       89       98       98  3.30  3.25       4
## 256  24   2      560       55       78       71  3.50  3.25       4
## 257  23   1      660       81       98       95  2.50  3.00       4
## 258  25   2      720       96       98       99  3.50  3.60       4
## 259  26   1      620       78       87       89  2.40  2.00       4
## 260  26   2      630       85       81       90  2.90  3.25       4
## 261  27   1      650       89       89       93  2.40  2.25       4
## 262  25   1      660       99       71       95  3.40  3.25       4
## 263  25   1      610       83       81       86  2.40  2.75       4
## 264  26   1      600       87       62       83  2.50  2.50       4
## 265  24   1      570       75       62       75  2.30  2.50       4
## 266  24   2      600       77       78       84  2.60  3.00       4
## 267  26   2      650       91       84       93  2.60  3.00       4
## 268  29   1      630       72       95       89  2.60  2.50       4
## 269  26   1      630       96       71       91  2.60  2.75       4
## 270  31   1      530       75       45       62  2.40  2.75       4
## 271  23   1      580       64       81       78  2.20  2.00       4
## 272  25   1      540       79       45       65  2.60  2.50       4
## 273  26   1      550       72       58       69  2.60  2.75       4
## 274  40   2      500       60       45       51  2.50  2.75       4
##     work_yrs frstlang salary satis
## 1          2        1      0     7
## 2          2        1      0     6
## 3          2        1      0     6
## 4          1        1      0     7
## 5          2        1    999     5
## 6          2        1      0     6
## 7          2        1      0     5
## 8          2        1      0     6
## 9          2        2    999     4
## 10         2        1    998   998
## 11         2        1    998   998
## 12         2        1    998   998
## 13         3        1    998   998
## 14         2        1    998   998
## 15         4        1    998   998
## 16         2        1    998   998
## 17         4        1    998   998
## 18         3        2    998   998
## 19         2        1    998   998
## 20         4        1    998   998
## 21         4        1    999     4
## 22         3        1      0     6
## 23         1        2      0     5
## 24         5        1      0     5
## 25         3        1      0     5
## 26         5        1    999     6
## 27        10        1      0     7
## 28         5        1      0     5
## 29         7        1      0     6
## 30         4        1    999     4
## 31         7        1      0     6
## 32         9        1      0     6
## 33        13        1      0     5
## 34        22        1      0     6
## 35         1        1  85000     5
## 36         2        1  85000     6
## 37         2        1  86000     5
## 38         3        1  88000     7
## 39         2        1  92000     6
## 40         5        1  93000     5
## 41         0        1  95000     4
## 42         1        1  95000     5
## 43         3        1  95000     3
## 44         1        1  96000     7
## 45         4        1  96000     5
## 46         2        1 100000     7
## 47         2        1 100000     6
## 48         6        1 100000     6
## 49         2        1 105000     7
## 50         3        1 105000     6
## 51         3        1 105000     6
## 52         2        1 105000     5
## 53         5        1 105000     6
## 54         6        1 105000     6
## 55         8        1 106000     7
## 56         6        1 106000     6
## 57         3        1 107500     5
## 58         3        1 108000     6
## 59         6        1 110000     5
## 60        16        1 112000     7
## 61         4        1 115000     5
## 62         1        1 115000     5
## 63        10        2 118000     7
## 64         3        1 120000     5
## 65         5        1 120000     5
## 66         5        1 120000     6
## 67         8        1 120000     6
## 68        15        1 146000     6
## 69         1        1 162000     5
## 70         1        1      0     5
## 71         2        1      0     7
## 72         0        2      0     5
## 73         2        1      0     6
## 74         1        1      0     5
## 75         3        1      0     4
## 76         2        1      0     5
## 77         2        1      0     6
## 78         3        1    999     5
## 79         2        2    998   998
## 80         2        1    998   998
## 81         3        1    998   998
## 82         2        2    998   998
## 83         2        1    998   998
## 84         3        1    998   998
## 85         2        1    998   998
## 86         2        1    998   998
## 87         3        1    999     1
## 88         3        1      0     6
## 89         3        1      0     6
## 90         4        2      0     5
## 91         2        1    999     4
## 92         5        1      0     5
## 93         3        1      0     6
## 94         4        1    998   998
## 95         4        1    998   998
## 96         4        2    998   998
## 97         4        1      0     6
## 98         5        1      0     6
## 99         4        1    999     3
## 100        1        1      0     6
## 101        4        2    999     4
## 102        5        1      0     5
## 103        3        1      0     5
## 104        7        1      0     5
## 105        6        1    999     5
## 106        4        1      0     6
## 107        4        1      0     5
## 108        4        1    999     6
## 109       11        1      0     7
## 110        8        1      0     5
## 111       12        1      0     5
## 112        7        1      0     5
## 113       18        1      0     6
## 114       16        1      0     5
## 115        1        1  82000     7
## 116        2        1  92000     5
## 117        8        1  93000     6
## 118        2        1  95000     6
## 119        3        1  95000     6
## 120        2        1  96000     7
## 121        2        1  96500     6
## 122        2        1  98000     6
## 123        2        1  98000     6
## 124        3        2  98000     5
## 125        5        2  99000     6
## 126        2        1 100000     5
## 127        4        1 100000     6
## 128        2        1 101000     5
## 129        3        1 103000     6
## 130        4        1 104000     5
## 131        3        1 105000     6
## 132        3        1 105000     5
## 133       16        1 105000     5
## 134        2        1 107000     5
## 135        6        1 112000     6
## 136        1        1 115000     6
## 137        4        1 115000     6
## 138        4        1 130000     7
## 139        2        1 145800     6
## 140        1        1      0     5
## 141        2        2      0     4
## 142        2        1      0     7
## 143        2        1      0     7
## 144        2        1      0     7
## 145        1        1    999     5
## 146        1        1      0     6
## 147        2        1      0     6
## 148        4        1    998   998
## 149        2        1    998   998
## 150        3        1      0     6
## 151        1        1      0     6
## 152        3        1    999     6
## 153        3        2    998   998
## 154        2        2    998   998
## 155        4        1    998   998
## 156        3        2    998   998
## 157        3        1    998   998
## 158        4        1    999     5
## 159        4        1      0     6
## 160        2        1      0     6
## 161        4        2    999     6
## 162        3        1      0     5
## 163        3        1      0     6
## 164        2        1      0     6
## 165        3        1      0     4
## 166        0        1    999     5
## 167        4        2      0     5
## 168        5        1      0     6
## 169        5        1      0     6
## 170        2        2    999     2
## 171        3        1    998   998
## 172        3        1    998   998
## 173        2        1    998   998
## 174        4        1    998   998
## 175        3        1    998   998
## 176        4        1    998   998
## 177        4        2    998   998
## 178        4        1    998   998
## 179        9        1    999     6
## 180        3        2      0     5
## 181        4        1    999     5
## 182        7        1      0     6
## 183       11        1      0     6
## 184       12        1      0     5
## 185       22        1      0     5
## 186        1        1  78256     5
## 187        3        1  88500     6
## 188        2        1  90000     7
## 189        2        1  90000     5
## 190        4        1  93000     6
## 191        5        1  95000     7
## 192        4        1  97000     7
## 193        3        1  97000     6
## 194        2        1  98000     7
## 195        2        1  98000     7
## 196        2        1  98000     6
## 197        2        2  98000     6
## 198        4        1  98000     7
## 199        7        1  98000     5
## 200        3        1 100000     6
## 201        2        1 100000     6
## 202        2        1 101000     6
## 203        8        1 101100     6
## 204        6        1 102500     5
## 205        2        1 105000     5
## 206        6        1 106000     6
## 207        2        2 107300     7
## 208        4        1 108000     6
## 209        2        1 112000     6
## 210        2        1    998   998
## 211        1        1    998   998
## 212        2        1    999     4
## 213        2        1      0     6
## 214        3        1    999     7
## 215        1        1    998   998
## 216        3        1    998   998
## 217        2        2    999     4
## 218        1        1      0     7
## 219        2        1      0     5
## 220        4        1      0     6
## 221        3        2    999     3
## 222        2        1      0     6
## 223        3        1    999     6
## 224        3        1    998   998
## 225        3        1    998   998
## 226        4        1    999     4
## 227        2        1      0     5
## 228        4        1    999     6
## 229        4        1      0     5
## 230        1        1      0     5
## 231        1        1    999     5
## 232        5        1      0     6
## 233        3        1      0     6
## 234        5        1      0     5
## 235        3        1    999     4
## 236        6        1      0     6
## 237        5        1      0     5
## 238        6        1      0     7
## 239        7        1    999     5
## 240        3        1    999     4
## 241        3        1      0     5
## 242        1        2      0     4
## 243        4        1      0     5
## 244        2        1      0     6
## 245        5        2    999     4
## 246        6        2    999     4
## 247        7        1    998   998
## 248        6        1    998   998
## 249        8        1    998   998
## 250        1        1      0     6
## 251        7        1    999     3
## 252        4        2    999     3
## 253        5        2      0     5
## 254        8        1      0     6
## 255        5        1      0     5
## 256        2        1  64000     7
## 257        2        1  77000     6
## 258        3        1  85000     6
## 259        2        1  85000     6
## 260        3        1  86000     5
## 261        5        1  90000     5
## 262        2        1  92000     7
## 263        2        1  95000     7
## 264        2        1  96000     6
## 265        2        1  98000     6
## 266        2        1 100000     6
## 267        2        1 100000     7
## 268        3        1 100400     7
## 269        3        1 101600     6
## 270        4        2 104000     6
## 271        2        1 105000     6
## 272        3        1 115000     5
## 273        3        1 126710     6
## 274       15        2 220000     6

SUMMARY OF THE DATA

summary(salary)
##       age             sex           gmat_tot        gmat_qpc    
##  Min.   :22.00   Min.   :1.000   Min.   :450.0   Min.   :28.00  
##  1st Qu.:25.00   1st Qu.:1.000   1st Qu.:580.0   1st Qu.:72.00  
##  Median :27.00   Median :1.000   Median :620.0   Median :83.00  
##  Mean   :27.36   Mean   :1.248   Mean   :619.5   Mean   :80.64  
##  3rd Qu.:29.00   3rd Qu.:1.000   3rd Qu.:660.0   3rd Qu.:93.00  
##  Max.   :48.00   Max.   :2.000   Max.   :790.0   Max.   :99.00  
##     gmat_vpc        gmat_tpc        s_avg           f_avg      
##  Min.   :16.00   Min.   : 0.0   Min.   :2.000   Min.   :0.000  
##  1st Qu.:71.00   1st Qu.:78.0   1st Qu.:2.708   1st Qu.:2.750  
##  Median :81.00   Median :87.0   Median :3.000   Median :3.000  
##  Mean   :78.32   Mean   :84.2   Mean   :3.025   Mean   :3.062  
##  3rd Qu.:91.00   3rd Qu.:94.0   3rd Qu.:3.300   3rd Qu.:3.250  
##  Max.   :99.00   Max.   :99.0   Max.   :4.000   Max.   :4.000  
##     quarter         work_yrs         frstlang         salary      
##  Min.   :1.000   Min.   : 0.000   Min.   :1.000   Min.   :     0  
##  1st Qu.:1.250   1st Qu.: 2.000   1st Qu.:1.000   1st Qu.:     0  
##  Median :2.000   Median : 3.000   Median :1.000   Median :   999  
##  Mean   :2.478   Mean   : 3.872   Mean   :1.117   Mean   : 39026  
##  3rd Qu.:3.000   3rd Qu.: 4.000   3rd Qu.:1.000   3rd Qu.: 97000  
##  Max.   :4.000   Max.   :22.000   Max.   :2.000   Max.   :220000  
##      satis      
##  Min.   :  1.0  
##  1st Qu.:  5.0  
##  Median :  6.0  
##  Mean   :172.2  
##  3rd Qu.:  7.0  
##  Max.   :998.0

STRUCTURE OF THE DATA

str(salary)
## 'data.frame':    274 obs. of  13 variables:
##  $ age     : int  23 24 24 24 24 24 25 25 25 25 ...
##  $ sex     : int  2 1 1 1 2 1 1 2 1 1 ...
##  $ gmat_tot: int  620 610 670 570 710 640 610 650 630 680 ...
##  $ gmat_qpc: int  77 90 99 56 93 82 89 88 79 99 ...
##  $ gmat_vpc: int  87 71 78 81 98 89 74 89 91 81 ...
##  $ gmat_tpc: int  87 87 95 75 98 91 87 92 89 96 ...
##  $ s_avg   : num  3.4 3.5 3.3 3.3 3.6 3.9 3.4 3.3 3.3 3.45 ...
##  $ f_avg   : num  3 4 3.25 2.67 3.75 3.75 3.5 3.75 3.25 3.67 ...
##  $ quarter : int  1 1 1 1 1 1 1 1 1 1 ...
##  $ work_yrs: int  2 2 2 1 2 2 2 2 2 2 ...
##  $ frstlang: int  1 1 1 1 1 1 1 1 2 1 ...
##  $ salary  : int  0 0 0 0 999 0 0 0 999 998 ...
##  $ satis   : int  7 6 6 7 5 6 5 6 4 998 ...

MEAN, MEDIAN AND STANDARD DEVIATION OF EACH VARIABLE

library(psych)
describe(salary)[,c(2,3,4,5,8,9)]
##            n     mean       sd median min    max
## age      274    27.36     3.71     27  22     48
## sex      274     1.25     0.43      1   1      2
## gmat_tot 274   619.45    57.54    620 450    790
## gmat_qpc 274    80.64    14.87     83  28     99
## gmat_vpc 274    78.32    16.86     81  16     99
## gmat_tpc 274    84.20    14.02     87   0     99
## s_avg    274     3.03     0.38      3   2      4
## f_avg    274     3.06     0.53      3   0      4
## quarter  274     2.48     1.11      2   1      4
## work_yrs 274     3.87     3.23      3   0     22
## frstlang 274     1.12     0.32      1   1      2
## salary   274 39025.69 50951.56    999   0 220000
## satis    274   172.18   371.61      6   1    998

NUMBER OF PLACED STUDENTS

Placed <- salary[ which(salary$salary > 999), c(1,2,12,13)]

VISUALISATION OF PLACED STUDENTS

#hist(Placed)

NUMBER OF UNPLACED STUDENTS

NotPlaced <- salary[ which(salary$salary == 0),c(1,2,11,12,13)]
NotPlaced
##     age sex frstlang salary satis
## 1    23   2        1      0     7
## 2    24   1        1      0     6
## 3    24   1        1      0     6
## 4    24   1        1      0     7
## 6    24   1        1      0     6
## 7    25   1        1      0     5
## 8    25   2        1      0     6
## 22   27   1        1      0     6
## 23   27   1        2      0     5
## 24   28   2        1      0     5
## 25   29   1        1      0     5
## 27   31   2        1      0     7
## 28   32   1        1      0     5
## 29   32   1        1      0     6
## 31   34   2        1      0     6
## 32   37   2        1      0     6
## 33   42   2        1      0     5
## 34   48   1        1      0     6
## 70   22   1        1      0     5
## 71   23   1        1      0     7
## 72   24   1        2      0     5
## 73   24   1        1      0     6
## 74   24   1        1      0     5
## 75   25   2        1      0     4
## 76   25   1        1      0     5
## 77   25   1        1      0     6
## 88   26   2        1      0     6
## 89   26   1        1      0     6
## 90   26   1        2      0     5
## 92   27   1        1      0     5
## 93   27   1        1      0     6
## 97   28   1        1      0     6
## 98   28   2        1      0     6
## 100  29   1        1      0     6
## 102  29   1        1      0     5
## 103  29   2        1      0     5
## 104  29   1        1      0     5
## 106  29   1        1      0     6
## 107  30   1        1      0     5
## 109  32   2        1      0     7
## 110  35   1        1      0     5
## 111  35   1        1      0     5
## 112  36   2        1      0     5
## 113  36   1        1      0     6
## 114  43   1        1      0     5
## 140  23   1        1      0     5
## 141  24   2        2      0     4
## 142  24   1        1      0     7
## 143  24   1        1      0     7
## 144  24   2        1      0     7
## 146  24   1        1      0     6
## 147  24   2        1      0     6
## 150  25   1        1      0     6
## 151  25   1        1      0     6
## 159  26   1        1      0     6
## 160  26   1        1      0     6
## 162  26   2        1      0     5
## 163  26   1        1      0     6
## 164  27   1        1      0     6
## 165  27   2        1      0     4
## 167  27   1        2      0     5
## 168  27   2        1      0     6
## 169  27   2        1      0     6
## 180  29   1        2      0     5
## 182  32   1        1      0     6
## 183  34   1        1      0     6
## 184  34   1        1      0     5
## 185  43   1        1      0     5
## 213  25   1        1      0     6
## 218  25   1        1      0     7
## 219  26   1        1      0     5
## 220  26   1        1      0     6
## 222  26   1        1      0     6
## 227  27   2        1      0     5
## 229  27   1        1      0     5
## 230  27   1        1      0     5
## 232  27   1        1      0     6
## 233  27   1        1      0     6
## 234  28   1        1      0     5
## 236  28   1        1      0     6
## 237  28   1        1      0     5
## 238  29   1        1      0     7
## 241  29   1        1      0     5
## 242  29   1        2      0     4
## 243  29   2        1      0     5
## 244  30   1        1      0     6
## 250  31   1        1      0     6
## 253  32   1        2      0     5
## 254  35   1        1      0     6
## 255  39   2        1      0     5

VISUALISATION OF UNPLACED STUDENTS

#hist(NotPlaced)

H1 - AGE DEPENDS ON THE STARTING SALARY OF A MBA STUDENT

my_table <- xtabs(~ age + salary, data = salary)
chisq.test(my_table)
## 
##  Pearson's Chi-squared test
## 
## data:  my_table
## X-squared = 1114.2, df = 880, p-value = 1.178e-07

H2 - SEX DEPENDS ON THE STARTING SALARY OF A MBA STUDENT

my_table1 <- xtabs(~ sex + salary, data = salary)
chisq.test(my_table1)
## 
##  Pearson's Chi-squared test
## 
## data:  my_table1
## X-squared = 63.727, df = 44, p-value = 0.0274

PLOT OF AGE VS SALARY

boxplot(salary ~ age, data = salary)

PLOT OF GENDER VS SALARY

library("lattice")
histogram( ~ salary | sex, data = salary)

PLOT OF TOTAL SCORE OF GMAT VS FIRST LANGUAGE

library(lattice)
boxplot(gmat_tot ~ frstlang, data = salary)

CORRELATIONS

library(car)
scatterplotMatrix(formula = ~ salary + age + sex + gmat_tot + frstlang , cex = 0.6,data= salary, diagonal = "histogram")

Correlation matirx

cor(salary) 
##                  age          sex    gmat_tot    gmat_qpc    gmat_vpc
## age       1.00000000 -0.028106442 -0.14593840 -0.21616985 -0.04417547
## sex      -0.02810644  1.000000000 -0.05336820 -0.16377435  0.07488782
## gmat_tot -0.14593840 -0.053368202  1.00000000  0.72473781  0.74839187
## gmat_qpc -0.21616985 -0.163774346  0.72473781  1.00000000  0.15218014
## gmat_vpc -0.04417547  0.074887816  0.74839187  0.15218014  1.00000000
## gmat_tpc -0.16990307 -0.008090213  0.84779965  0.65137754  0.66621604
## s_avg     0.14970402  0.127115144  0.11311702 -0.02984873  0.20445365
## f_avg    -0.01744806  0.091663891  0.10442409  0.07370455  0.07592225
## quarter  -0.04967221 -0.133533171 -0.09223903  0.03636638 -0.17460736
## work_yrs  0.85829810 -0.011296374 -0.18235434 -0.23660827 -0.06639049
## frstlang  0.05692649  0.001536205 -0.13503402  0.13892774 -0.38980465
## salary   -0.06257355  0.068858628 -0.05497188 -0.04403293 -0.00613934
## satis    -0.12788825 -0.054602220  0.08255770  0.06060004  0.06262375
##              gmat_tpc       s_avg       f_avg       quarter     work_yrs
## age      -0.169903066  0.14970402 -0.01744806 -4.967221e-02  0.858298096
## sex      -0.008090213  0.12711514  0.09166389 -1.335332e-01 -0.011296374
## gmat_tot  0.847799647  0.11311702  0.10442409 -9.223903e-02 -0.182354339
## gmat_qpc  0.651377538 -0.02984873  0.07370455  3.636638e-02 -0.236608270
## gmat_vpc  0.666216035  0.20445365  0.07592225 -1.746074e-01 -0.066390490
## gmat_tpc  1.000000000  0.11736245  0.07973210 -8.303535e-02 -0.173361859
## s_avg     0.117362449  1.00000000  0.55062139 -7.621166e-01  0.129292714
## f_avg     0.079732099  0.55062139  1.00000000 -4.475064e-01 -0.039056921
## quarter  -0.083035351 -0.76211664 -0.44750637  1.000000e+00 -0.086026406
## work_yrs -0.173361859  0.12929271 -0.03905692 -8.602641e-02  1.000000000
## frstlang -0.103362747 -0.13631308 -0.03705695  9.949226e-02 -0.027866747
## salary    0.004930901  0.14583606  0.02944303 -1.643699e-01  0.009023407
## satis     0.092934266 -0.03268664  0.01089273 -1.267198e-05 -0.109255286
##              frstlang       salary         satis
## age       0.056926486 -0.062573547 -1.278882e-01
## sex       0.001536205  0.068858628 -5.460222e-02
## gmat_tot -0.135034017 -0.054971880  8.255770e-02
## gmat_qpc  0.138927742 -0.044032933  6.060004e-02
## gmat_vpc -0.389804653 -0.006139340  6.262375e-02
## gmat_tpc -0.103362747  0.004930901  9.293427e-02
## s_avg    -0.136313080  0.145836062 -3.268664e-02
## f_avg    -0.037056954  0.029443027  1.089273e-02
## quarter   0.099492259 -0.164369865 -1.267198e-05
## work_yrs -0.027866747  0.009023407 -1.092553e-01
## frstlang  1.000000000 -0.086592096  7.932264e-02
## salary   -0.086592096  1.000000000 -3.352171e-01
## satis     0.079322637 -0.335217114  1.000000e+00

CORRELATION TEST

library(corrplot)
library(gplots)
library(Hmisc)

colsalary <- c( "salary","age","sex","gmat_tot","frstlang")
corMatrix <- rcorr(as.matrix(salary[,colsalary]))
corMatrix
##          salary   age   sex gmat_tot frstlang
## salary     1.00 -0.06  0.07    -0.05    -0.09
## age       -0.06  1.00 -0.03    -0.15     0.06
## sex        0.07 -0.03  1.00    -0.05     0.00
## gmat_tot  -0.05 -0.15 -0.05     1.00    -0.14
## frstlang  -0.09  0.06  0.00    -0.14     1.00
## 
## n= 274 
## 
## 
## P
##          salary age    sex    gmat_tot frstlang
## salary          0.3020 0.2560 0.3647   0.1529  
## age      0.3020        0.6432 0.0156   0.3479  
## sex      0.2560 0.6432        0.3789   0.9798  
## gmat_tot 0.3647 0.0156 0.3789          0.0254  
## frstlang 0.1529 0.3479 0.9798 0.0254

CORRGRAM PLOT

library(car)
library(corrgram)
library(Hmisc)

corrgram(salary[,colsalary], order = TRUE,
         main = "SALARY OF MALE AND FEMALE",
         lower.panel = panel.pts,upper.panel = panel.pie,
         diag.panel = panel.minmax, text.panel = panel.txt)

T-TEST OF FIRST LAGUAGE AND TOTAL GMAT SCORE

t.test(salary$frstlang,salary$gmat_tot)
## 
##  Welch Two Sample t-test
## 
## data:  salary$frstlang and salary$gmat_tot
## t = -177.88, df = 273.02, p-value < 2.2e-16
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
##  -625.1791 -611.4924
## sample estimates:
##  mean of x  mean of y 
##   1.116788 619.452555

T-TEST OF SALARY AND AGE

t.test(salary$salary,salary$age)
## 
##  Welch Two Sample t-test
## 
## data:  salary$salary and salary$age
## t = 12.67, df = 273, p-value < 2.2e-16
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
##  32938.51 45058.15
## sample estimates:
##   mean of x   mean of y 
## 39025.68978    27.35766

T-TEST OF SALARY AND SEX

t.test(salary$salary,salary$sex)
## 
##  Welch Two Sample t-test
## 
## data:  salary$salary and salary$sex
## t = 12.678, df = 273, p-value < 2.2e-16
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
##  32964.62 45084.26
## sample estimates:
##    mean of x    mean of y 
## 39025.689781     1.248175

FORMULATING MULTIVARIATE LINEAR REGRESSION MODEL TO FIT SALARY WITH RESPECT TO OTHER VARAIBLES

Model <- salary ~ . 
fit <- lm(Model, data = salary)
summary(fit)
## 
## Call:
## lm(formula = Model, data = salary)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -77353 -42055  -4193  43432 204537 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 215476.47   74731.74   2.883  0.00426 ** 
## age          -3841.82    1578.26  -2.434  0.01560 *  
## sex           1810.69    6853.24   0.264  0.79183    
## gmat_tot      -278.09     209.44  -1.328  0.18540    
## gmat_qpc       334.82     578.64   0.579  0.56333    
## gmat_vpc       294.13     550.38   0.534  0.59351    
## gmat_tpc       512.59     417.03   1.229  0.22012    
## s_avg        12836.84   12919.75   0.994  0.32135    
## f_avg        -6371.67    6636.87  -0.960  0.33792    
## quarter      -5443.82    4050.86  -1.344  0.18016    
## work_yrs      2881.46    1784.27   1.615  0.10753    
## frstlang     -3058.63   10365.65  -0.295  0.76817    
## satis          -47.17       7.84  -6.016 6.01e-09 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 47130 on 261 degrees of freedom
## Multiple R-squared:  0.1818, Adjusted R-squared:  0.1442 
## F-statistic: 4.834 on 12 and 261 DF,  p-value: 3.555e-07

FINDING THE BEST PREDICTORS

library(leaps)
leap1 <- regsubsets(Model,data = salary, nbest = 1)
plot(leap1, scale = "adjr2")

## REVISING THE MODEL

Model1 <- salary ~ age + gmat_tot + gmat_tpc + quarter + work_yrs + satis 
fit1 <- lm(Model1, data = salary)
summary(fit1)
## 
## Call:
## lm(formula = Model1, data = salary)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -70813 -41036  -4206  43065 199904 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 212040.118  49365.781   4.295 2.45e-05 ***
## age          -3778.530   1501.671  -2.516  0.01245 *  
## gmat_tot      -174.240     93.673  -1.860  0.06397 .  
## gmat_tpc       640.571    383.667   1.670  0.09617 .  
## quarter      -7593.684   2579.792  -2.944  0.00353 ** 
## work_yrs      2954.050   1731.271   1.706  0.08912 .  
## satis          -47.998      7.705  -6.230 1.81e-09 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 46790 on 267 degrees of freedom
## Multiple R-squared:  0.1751, Adjusted R-squared:  0.1566 
## F-statistic: 9.448 on 6 and 267 DF,  p-value: 2.059e-09

VISUALISING THE BETA COEFFICIENTS AND THEIR CONFIDENCE INTERVALS FROM MODEL1

library(coefplot)
coefplot(fit,intercept = FALSE,outerCI = 1.96,coefficients = c("age","gmat_tot" ,"gmat_tpc", "quarter","work_yrs" , "satis"))

MODEL 1 FITS BETTER THAN MODEL, AS INDICATED BY ADJUSTED R SQUARE

summary(fit)$adj.r.squared
## [1] 0.1442077
summary(fit1)$adj.r.squared
## [1] 0.1566027

INTERACTION PLOTS BETWEEN AGE, SEX AND SALARY

interaction.plot(salary$age,salary$sex,salary$salary, type = "b",
            col = c("red","blue"),pch = c(16,18),
            main = "Interaction between gender and salary")

INTERACTION PLOTS BETWEEN FIRST LANGUAGE, SATIFACTION RATING AND SALARY

interaction.plot(salary$satis,salary$frstlang,salary$salary, type = "b",
            col = c("red","blue"),pch = c(16,18),
            main = "Interaction between gender and salary")

## RESULT INTERPRETATION ## THE COEFFICIENTS, “age”,“gmat_tot” ,“gmat_tpc”, “quarter”,“work_yrs” , “satis” ARE STATISTICALLY SIGNIFICANT WITH THE CHANGE IN STARTING SALARIES.

The regression coefficient (212040.118) is significantly dfferent from zero (p < 0.001)

There is an expected increase of price of 0.61 for every 18 min increase in the flight duration.

THE MULTIPLE R-SQUARED (0.1751) INDICATES THAT THE MODEL ACCOUNTS FOR 17.51% OF THE VARIANCE IN the SALARIES

THE RESIDUAL STANDARD ERROR (46790) CAN BE THOUGHT OF AS THE AVERAGE ERROR IN PREDICTING THE SALARIES USING THIS MODEL

THE F-STATISITCS PREDICT THAT THE MODEL IS HIGHLY SIGNIFICANT AS P-VALUE IS 2.059e-09 (p< 0.001)