Question

In: Statistics and Probability

A researcher classifies firefighters according to whether their gloves fit well or poorly and by gender....

A researcher classifies firefighters according to whether their gloves fit well or poorly and by gender. They want to know if there is a difference in the proportion of poorly fitted gloves and gender. At alpha = 0.01, use the chi-square test to determine if there is a difference in the population proportion of glove fitness for the two genders. Using the observed data in the table, determine the percentage of gloves that fit poorly for each gender (fit poorly/total). Which gender has higher percentage of poorly fit gloves? Why?

Observed data

Males

Females

Total

Gloves fit poorly

132

20

152

Gloves fit well

415

19

434

Total

547

39

586

Expected data

Males

Females

Total

Gloves fit poorly

Gloves fit well

Total

Solutions

Expert Solution

Expected frequency of a cell = sum of row*sum of column / total sum
Expected Frequencies
Males Females Total
Gloves fit poorly 547*152/586=141.884 39*152/586=10.116 152
Gloves fit well 547*434/586=405.116 39*434/586=28.884 434
Total 547 39 586

Chi-Square Test Statistic,χ² = Σ(fo-fe)^2/fe =   13.9691  
      
Level of Significance =   0.01  
Number of Rows =   2  
Number of Columns =   2  
Degrees of Freedom=(#row - 1)(#column -1) = (2- 1 ) * ( 2- 1 ) =   1  
      
p-Value =   0.0002   [Excel function: =CHISQ.DIST.RT(χ²,df) ]
Decision:    p-value < α , Reject Ho  

conclusion:  there is a difference in the population proportion of glove fitness for the two genders

=============

percentage of gloves that fit poorly for male=132/547=24.13%

percentage of gloves that fit poorly for female=20/39=51.28%

Female  gender has higher percentage of poorly fit gloves


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