Question

Corporate advertising tries to enhance the image of the corporation. A study compared two ads from two sources, the Wall Street Journal and the National Enquirer. Subjects were asked to pretend that their company was considering a major investment in Performax, the fictitious sportswear firm in the ads. Each subject was asked to respond to the question "How trustworthy was the source in the sportswear company ad for Performax?" on a 7-point scale. Higher values indicated more trustworthiness. Here is a summary of the results.

Ad source n x s

Wall Street Journal 66 4.77 1.50

National Enquirer 61 2.43 1.64

Find the two-sample pooled t statistic. Then formulate the problem as an ANOVA and report the results of this analysis. Verify that F = t^2.

Answer 1

Here we have

Pooled standard deviation is :

and t-statistics will be

-------------------

Folloiwng is the ANOVA generated by the summary statistics:

Source of variation	SS	DF	MS	F
Between	173.5808	1	173.5808	70.5324
Within	307.626	125	2.461
Total	481.2068	126

And from ANOVA

Hence,