An employment agency wants to see which of three types of ad

An employment agency wants to see which of three types of ads in the help-wanted section of local newspapers is the most effective. Three types of ads (big headlines, straightforward, and bold print) were randomly alternated over a period of weeks, and the number of people responding to the ads was noted each week.

Do these data support the null hypothesis that there is no difference in the effectiveness of the ads, as measured by the mean number responding, at the .01 level of significance?

(a) Find the test statistic. (Give your answer correct to two decimal places.)


(b) Find the critical value. (Give your answer correct to two decimal places.)

(c) State the appropriate conclusion.

Solution

(a) The test statistic is F=3.57

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(b) Given a=0.01, the critical value is F(0.99, df1=2, df2=14) =6.51 (from F table)

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(c) Since F=3.57 is less than 6.51, we do not reject the null hypothesis.

So we can conclude that there is no difference in the effectiveness of the ads