Question

A study carried out by Nielsen/ Net Ratings in the last August 2001 indicated that the average number of Internet sessions at home per month was 34. In the following September, they conducted a study and recorded the number of Internet sessions at home for a random sample of 100 Internet users. The average number of Internet sessions was 32 with standard deviation equal to 4.5. Compute a statistical test to determine if the number of Internet sessions decreased from August to September?

a. Write down the test hypotheses, the test statistic and the p-value.

b. What conclusions can you draw?

Answer 1

a)

H0: = 34

Ha: < 34

Test statistics

t = ( - ) / (S / sqrt(n) )

= ( 32 - 34) / ( 4.5 / sqrt(100) )

= -4.44

df = n - 1 = 100 - 1 = 99

From T table,

With test statistics of 4.44 and df of 99

p-value = 0.0000

b)

Since p-value < 0.05, Reject the null hypothesis.

Conclusion - We conclude that we have sufficient evidence to support the claim that

the number of Internet sessions decreased from August to September.