lesson_02

bw = read.csv("/Users/tramanhvo/Downloads/bw_file.csv", header=T, na.strings = "")

Assign factor (discontinuous data values) to “race” variable numbers & create a new column to record those values.

bw$ethnicity [bw$race==1] <- "White"
bw$ethnicity [bw$race==2] <- "Black"
bw$ethnicity [bw$race==3] <- "Other"

Add new column that replaces binary numbers for “Smoking” variable with “Yes”/“No”.

bw$smoking = ifelse(bw$smoke==1, "Yes", "No")

Add new column that replaces binary numbers for “low.bwt” variable with “Yes”/“No”.

bw$low.bwt = ifelse(bw$low==1, "Yes", "No")

Print current table (first 10 rows).

head(bw, 10)

##    id low age lwt race smoke ptl ht ui ftv  bwt ethnicity smoking low.bwt
## 1  85   0  19 182    2     0   0  0  1   0 2523     Black      No      No
## 2  86   0  33 155    3     0   0  0  0   3 2551     Other      No      No
## 3  87   0  20 105    1     1   0  0  0   1 2557     White     Yes      No
## 4  88   0  21 108    1     1   0  0  1   2 2594     White     Yes      No
## 5  89   0  18 107    1     1   0  0  1   0 2600     White     Yes      No
## 6  91   0  21 124    3     0   0  0  0   0 2622     Other      No      No
## 7  92   0  22 118    1     0   0  0  0   1 2637     White      No      No
## 8  93   0  17 103    3     0   0  0  0   1 2637     Other      No      No
## 9  94   0  29 123    1     1   0  0  0   1 2663     White     Yes      No
## 10 95   0  26 113    1     1   0  0  0   0 2665     White     Yes      No

Create table using the table1 function, with “ethincity” as colunns and the variables in front as rows. The talbe will also show stdev, mean, and other statistical values.

echo=FALSE prevents code that creates the chart from being shown.

	Black (N=26)	Other (N=67)	White (N=96)	Overall (N=189)
age
Mean (SD)	21.5 (5.11)	22.4 (4.54)	24.3 (5.65)	23.2 (5.30)
Median [Min, Max]	20.5 [15.0, 35.0]	22.0 [14.0, 33.0]	23.5 [14.0, 45.0]	23.0 [14.0, 45.0]
smoking
No	16 (61.5%)	55 (82.1%)	44 (45.8%)	115 (60.8%)
Yes	10 (38.5%)	12 (17.9%)	52 (54.2%)	74 (39.2%)
low.bwt
No	15 (57.7%)	42 (62.7%)	73 (76.0%)	130 (68.8%)
Yes	11 (42.3%)	25 (37.3%)	23 (24.0%)	59 (31.2%)
bwt
Mean (SD)	2720 (639)	2810 (722)	3100 (728)	2940 (729)
Median [Min, Max]	2850 [1140, 3860]	2840 [709, 4050]	3060 [1020, 4990]	2980 [709, 4990]