10.12 Page 344. Two Sample t-test regarding (2) population means. 10.12 Page 344. ANOVA Method. 10.12 Page 344. ANOVA Method. Think of the F distribution as the t distribution squared. All F-tests are one-tail tests. For a 2-tailed t-test, the area in the two-tails are combined.
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Two Sample t-test regarding (2) population means
All F-tests are one-tail tests.
For a 2-tailed t-test, the area in the two-tails are combined.
All F values are positive.
Notice (from the first slide) t*=-4.1343, and (-4.1343)2=17.09
The single factor is the Ad influencing the Rating.
There is evidence of a difference in the mean rating of the five advertisements.
j=6 observations in each group
mean group B
mean group C
mean group D
mean group E
SSA, measure of variation in means among groups
SSW, measure of variation within group
SST, measure of TOTAL variation
If the absolute value of the mean difference in a pair is greater than the Critical Range (CR) value, the difference is significant.
The CR is obtained from the Q, Studentized Range distribution, with dfnum=c and dfdenom=n-c.
F distribution test, dfnum=c-1, dfdenom=n-c
T-K all pairs test
Q distribution test, dfnum=c, dfdenom=n-c
Perform the T-K procedure manually and in NCSS.
If you have time, try to obtain SSA, SSW, and SST manually with the use of Excel. Be able to
Compute MSA and MSW from SSA and SSW.
Compute F* and Fcrit and interpret.
Obtain Q Critical Range value and perform the T-K procedure to compare means of pairs.