Problem 1 :

Employment

A employment survey provided data showing the typical annual salary for 97 different jobs.The data is in file JobSalary.csv. Test the difference in mean annual salary for 3 categories: Computers, Construction and Engg.

Loading the csv file

js <- read.csv("F:\\Statistics\\Testing of Hypothesis\\JobSalary.csv")
head(js)

Analysis of Variance Test

anl <- aov(js$Salary_000 ~ js$Category)
summary(anl)
            Df Sum Sq Mean Sq F value   Pr(>F)    
js$Category  2   3840  1919.8   15.64 6.94e-05 ***
Residuals   21   2578   122.8                     
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Tukey’s Test

TukeyHSD(anl)
  Tukey multiple comparisons of means
    95% family-wise confidence level

Fit: aov(formula = js$Salary_000 ~ js$Category)

$`js$Category`
                         diff        lwr       upr     p adj
Construction-Computer -24.375 -38.339381 -10.41062 0.0007019
Engineer-Computer       4.375  -9.589381  18.33938 0.7133080
Engineer-Construction  28.750  14.785619  42.71438 0.0001096
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