Linear Regression

Lab 1

rm(list=ls())

getwd()
## [1] "C:/AGZ1/GD_AGZ1117/AGZ_Home/workspace_R/Asif_06_2018"
ls()
## character(0)
setwd("C:/AGZ1/GD_AGZ1117/AGZ_Home/workspace_R")

LoadLibraries=function (){
  library (ISLR)
  library (MASS)
  library(dplyr)
  library(tidyr)
  library(sqldf)
  library(ggplot2)
  print ("The libraries have been loaded .")
}

LoadLibraries()
## 
## Attaching package: 'dplyr'
## The following object is masked from 'package:MASS':
## 
##     select
## The following objects are masked from 'package:stats':
## 
##     filter, lag
## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union
## Loading required package: gsubfn
## Loading required package: proto
## Loading required package: RSQLite
## [1] "The libraries have been loaded ."
getwd()
## [1] "C:/AGZ1/GD_AGZ1117/AGZ_Home/workspace_R"
data = read.csv("data/dataset-1.csv")
head(data)
##           x         y
## 1  5.325177 11.003381
## 2 -1.017725  1.829188
## 3  9.334208 24.211486
## 4  7.818031 16.930033
## 5  3.161936 10.991406
## 6 -6.296965 -6.661919
fraction = 0.8
subset.rows = sample(nrow(data), floor(nrow(data) * fraction))

training = data[subset.rows,]
testing = data[-subset.rows,]

dim(data)
## [1] 99  2
dim(training)
## [1] 79  2
dim(testing)
## [1] 20  2
summary(data)
##        x                 y          
##  Min.   :-9.6907   Min.   :-20.630  
##  1st Qu.:-5.2669   1st Qu.: -7.658  
##  Median :-0.3784   Median :  2.476  
##  Mean   :-0.2800   Mean   :  2.843  
##  3rd Qu.: 4.2545   3rd Qu.: 13.019  
##  Max.   : 9.9298   Max.   : 27.737
attach(data)

# ?attach
plot(x, y)

model = lm(y ~ x)

summary(model)
## 
## Call:
## lm(formula = y ~ x)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -4.5966 -1.9969  0.2185  2.0410  4.2002 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  3.45196    0.24178   14.28   <2e-16 ***
## x            2.17592    0.04093   53.16   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 2.403 on 97 degrees of freedom
## Multiple R-squared:  0.9668, Adjusted R-squared:  0.9665 
## F-statistic:  2826 on 1 and 97 DF,  p-value: < 2.2e-16
lm(formula = y ~ x)
## 
## Call:
## lm(formula = y ~ x)
## 
## Coefficients:
## (Intercept)            x  
##       3.452        2.176
plot(fitted(model))

residuals(model)
##           1           2           3           4           5           6 
## -4.03572706  0.59170882  0.44906158 -3.53331717  0.65933290  3.58778939 
##           7           8           9          10          11          12 
##  3.54629286 -4.06053113  2.02136410  2.85318273 -2.32401804  4.18271806 
##          13          14          15          16          17          18 
## -4.59663379  0.79126758  3.49138025 -0.82208806 -0.47243498  2.67837278 
##          19          20          21          22          23          24 
##  1.09524097 -2.25799327  1.14858569  1.52530442  2.09151494 -3.48659143 
##          25          26          27          28          29          30 
##  0.32073371  1.53499868 -3.33790061 -1.82220766 -4.50022113 -3.00643918 
##          31          32          33          34          35          36 
##  0.23779328  2.42592540 -0.77503003  0.59615358 -3.16726961  4.20015315 
##          37          38          39          40          41          42 
## -0.54185728  3.73828500  2.78703616  0.49290206 -2.88272498  1.03847473 
##          43          44          45          46          47          48 
##  2.07903815  1.12973488 -1.53461004 -3.05760475 -1.48496269 -0.73810076 
##          49          50          51          52          53          54 
## -1.58121437 -0.76918178 -2.21555130  0.30591902  3.36979405 -3.23005505 
##          55          56          57          58          59          60 
##  0.21846080 -3.19269741 -0.59593447 -0.01343787 -0.70769795  0.17565969 
##          61          62          63          64          65          66 
##  0.61701897  3.00589091  0.28631983  3.24279248 -1.38605071  0.63716817 
##          67          68          69          70          71          72 
## -0.59277774  2.06055361 -1.69066773 -1.69572798  3.31569446  2.10840095 
##          73          74          75          76          77          78 
## -2.38278008 -2.17160019 -2.51187933 -1.18581227  2.85107947 -2.92556780 
##          79          80          81          82          83          84 
## -0.62134052  2.56772594 -2.24010073  4.02391986  0.30520777  1.54305529 
##          85          86          87          88          89          90 
##  3.74893566 -2.84634580 -0.23161659  1.88933241 -1.29307022  1.62688857 
##          91          92          93          94          95          96 
##  4.12530449 -4.17763891  1.20159094  0.01972528 -3.38833795  2.16245722 
##          97          98          99 
## -2.83542636  2.69876340 -0.48123029
confint(model)
##                2.5 %   97.5 %
## (Intercept) 2.972092 3.931836
## x           2.094684 2.257150