case0601: Discrimination Against the Handicapped

In Sleuth3: Data Sets from Ramsey and Schafer's "Statistical Sleuth (3rd Ed)"

Discrimination Against the Handicapped

Description

Study explores how physical handicaps affect people's perception of employment qualifications. Researchers prepared 5 videotaped job interviews using actors with a script designed to reflect an interview with an applicant of average qualifications. The 5 tapes differed only in that the applicant appeared with a different handicap in each one. Seventy undergraduate students were randomly assigned to view the tapes and rate the qualification of the applicant on a 0-10 point scale.

Usage

case0601

Format

A data frame with 70 observations on the following 2 variables.

Score

is the score each student gave to the applicant

Handicap

is a factor variable with 5 levels—"None", "Amputee", "Crutches", "Hearing" and "Wheelchair"

Source

Ramsey, F.L. and Schafer, D.W. (2013). The Statistical Sleuth: A Course in Methods of Data Analysis (3rd ed), Cengage Learning.

References

Cesare, S.J., Tannenbaum, R.J. and Dalessio, A. (1990). Interviewers' Decisions Related to Applicant Handicap Type and Rater Empathy, Human Performance 3(3): 157–171.

Examples

str(case0601) 
attach(case0601) 

## EXPLORATION
myHandicap  <- factor(Handicap,  
  levels=c("None","Amputee","Crutches","Hearing","Wheelchair"))  
boxplot(Score ~ myHandicap, 
  ylab= "Qualification Score Assigned by Student to Interviewee",  
  xlab= "Treatment Group--Handicap Portrayed (14 Students in each Group)", 
  main= "Handicap Discrimination Experiment on 70 Undergraduate Students") 
myAov  <- aov(Score ~ myHandicap) 
plot(myAov, which=1) # Plot residuals versus estimated means 
summary(myAov) 

## COMPARE MEAN QUALIFICATION SCORE OF EVERY HANDICAP GROUP TO "NONE"  
if(require(multcomp)){     # Use the multcomp library
  myDunnett  <- glht(myAov, linfct = mcp(myHandicap = "Dunnett"))  
  summary(myDunnett) 
  confint(myDunnett,level=.95) 
  opar <- par(no.readonly=TRUE)  # Save current graphics parameter settings
  par(mar=c(4.1,8.1,4.1,1.1)) # Change margins 
  plot(myDunnett, 
    xlab="Difference in Mean Qualification Score (and Dunnet-adjusted CIs)") 
  par(opar)  # Restore original graphics parameter settings
} 

## COMPARE EVERY MEAN TO EVERY OTHER MEAN
if(require(multcomp)){   # Use the multcomp library
  myTukey   <- glht(myAov, linfct = mcp(myHandicap = "Tukey"))  
  summary(myTukey) 
}

## TEST THE CONTRAST OF DISPLAY 6.4
myAov2        <- aov(Score ~ myHandicap - 1)    
myContrast    <- rbind(c(0, -1/2, 1/2, -1/2, 1/2)) 
if(require(multcomp)){   # Use the multcomp library
  myComparison  <- glht(myAov2, linfct=myContrast)
  summary(myComparison, test=adjusted("none"))  
  confint(myComparison)  
}  


# BOXPLOTS FOR PRESENTATION   
boxplot(Score ~ myHandicap, 
  ylab= "Qualification Score Assigned by Student to Video Job Applicant",  
  xlab="Handicap Portrayed by Job Applicant in Video (14 Students in each Group)",  
  main= "Handicap Discrimination Experiment on 70 Undergraduate Students", 
  col="green", boxlwd=2, medlwd=2, whisklty=1, whisklwd=2, staplewex=.2,  
	staplelwd=2, outlwd=2, outpch=21,  outbg="green", outcex=1.5) 
	
detach(case0601) 

Sleuth3 documentation built on May 29, 2024, 2:56 a.m.