Question:

6) One reason that direct marketing techniques have become so popular for internet advertising is that they offer ample opportunity to test new concepts in an experimental context. For example, Bob just read that using an orange "submit order" button increases both number of orders submitted and the average amount of an order. Bob knows that such "findings" often vary from site to site. Since he does not care at all about any other site, he decides to test this idea using an experiment on his site.

He randomly assigns 500 regular customers to see the orange submit order button when they visit his site, while the remaining regular customers continue to see the regular white submit button.

He looks at sales from the previous month for the 500 test subjects and finds the average sale is $75.50; the average previous month sale for the remaining regular customers is $77.00.

After a one month test, he finds that the test group (the 500 orange button customers) has an average sales amount of $90.00, while the remaining regular customers have an average sales amount of $86.50.

Bob performs a two-tailed difference of means test. Assume his boss uses an alpha level of .05, and Bob finds a p-value of .002.

a) What is your best estimate of the quantitative effects of the orange submit order button? How did you arrive at this answer? (6 points) (I am not looking for a statistical analysis here, but I would like to see a number.)

b) Identify and explain one threat to internal validity which is NOT a problem here, given the design of the experiment. (6 points) In what sense is this threat "controlled for?" (6 points)

c) In general, do you think these results have relatively high or low external validity? Why?

Question 17 4 pts Which of the following statements is NOT consistent with the Central Limit Theorem? O The Central Limit Theorem indicates that the mean of the sampling distribution will be equal to the population mean. O The Central Limit Theorem indicates that the sampling distribution will be approximately normal when the sample size is sufficiently large. O The Central Limit Theorem applies to non-normal distributions. O The Central Limit Theorem applies without regard to the size of the sample.Which of the following statements are TRUE regarding Central Limit Theorem? CCS The central limit theorem gives the exact probability of estimating the true population mean. Chart / Roll The central limit theorem only applies when the population distribution is normal. The range of values for the sampling distribution of means is larger than the range of values in the population. The central limit theorem requires that all samples are randomly selected from a single population.Question 21 4 If you don't know whether the frequency distribution is normally distributed. O You can use both the Empirical Rule and the Central Limit Theorem O You can't use the Empirical Rule, but you can use the Central Limit Theorem O You can't use the Central Limit Theorem, but you can use the Empirical Rule You can't use either the Empirical Rule or the Central Limit Theorem