Question

A researcher is interested in whether there is a significant difference between the mean age of marriage across three racial groups. Using the data provided below, conduct an F-test to determine whether you believe there is an association between race and average age at marriage.

Race N Mean
Black 113 25.39
White 904 22.99
Other 144 23.87
All Groups 1,161 23.33

Answer 1

The P-value is < significance value ( 0.05 ) hence we reject the Null hypothesis ( i.e. There is an association between the race and average age at marriage )

Explanation:

Conducting an F-test to determine association between race and average age at marriage

step 1 : State the hypothesis

H0 : ц1 = ц2 = ц3

Ha : ц1 ≠ ц2 ≠ ц3

step 2 : determine the mean square between

Given mean value of all groups = 23.33

SS btw = 113*(25.39 - 23.33)² + 904*(22.99 - 23.33)² + 144*(23.89 - 23.33)^2 = 113(4.2436) + 904(0.1156) + 144(0.3136)

= 629.1876

hence: df btw = 3 - 1 = 2

df total = 1161 - 1 = 1160

df within = 1160 - 2 = 1158

SS within = 36.87*1158 = 42695.46

Therefore the MS between = 629.19 / 2 = 314.60

The F-ratio = 314.59 / 36.87 = 8.53

using the values for Btw the P-value = 0.00021

The P-value is < significance value ( 0.05 ) hence we reject the Null hypothesis ( i.e. There is an association between the race and average age at marriage )