Question

Do this homework by R and put the syntax of R and corresponding outputs under respective questions. Do not turn in separate pages of R commands and outputs, such homework will not be graded. Therefore edit your homework accordingly.

1. A national equal employment opportunities committee is conducting an investigation to determine if women employees are as well paid as their male counterparts in comparable jobs. Random samples of 75 males and 64 females in junior academic positions are selected and their salary data is stored in “salaries.csv”. (a) Find the mean and the standard deviation of each group.

Data:

gender	income
Male	48932
Male	48281
Male	49885
Male	48646
Male	49391
Male	48824
Male	49459
Male	48685
Male	49932
Male	48779
Male	47685
Male	48984
Male	48616
Male	47362
Male	46919
Male	47676
Male	47932
Male	48494
Male	49161
Male	48201
Male	48089
Male	48287
Male	48028
Male	48240
Male	48312
Male	47827
Male	47839
Male	48578
Male	49740
Male	48942
Male	49759
Male	48134
Male	47934
Male	47702
Male	46989
Male	48716
Male	49599
Male	48713
Male	49089
Male	48452
Male	48097
Male	47012
Male	48584
Female	46737
Female	48929
Female	47321
Female	47952
Female	47958
Female	47563
Female	47843
Female	46724
Female	46122
Female	48661
Female	47558
Female	47914
Female	46808
Female	48822
Female	48373
Female	47905
Female	47196
Female	46710
Female	46597
Female	47727
Female	47421
Female	47244
Female	48538
Female	47944
Female	47615

I know the two commands for entering it in are

salaries=read.table("C:/Data/salaries.csv",sep=",")

names(salaries)=c("gender","income")

But when i try to get the mean, it gives me :

mean(salaries$income,na.rm=T)
[1] NA
Warning message:
In mean.default(salaries$income, na.rm = T) :
argument is not numeric or logical: returning NA

Answer 1

I stored the data set that you provided above in a .csv file and then ran the following R commands and I got the following output. The command lines are given in bold.

> salaries=read.csv("C:/Users/DGDesktop/Desktop/salaries.csv")
> aggregate(salaries$income,by=list(salaries$gender),FUN=mean)
Group.1 x
1 Female 47607.28
2 Male 48476.88
> aggregate(salaries$income,by=list(salaries$gender),FUN=sd)
Group.1 x
1 Female 736.6504
2 Male 764.1954

So, after the two commands that you gave you need to give these two command lines to get the mean and standard deviation:
aggregate(salaries$income,by=list(salaries$gender),FUN=mean)
aggregate(salaries$income,by=list(salaries$gender),FUN=sd)