SOLUTION: The Flynn effect posits that over time there are IQ gains such that if a sample is re-tested on a previous test then the mean is no longer 100 (Flynn Effect, n.d.). It is also

Click here to see ALL problems on Probability-and-statistics

Question 918665: The Flynn effect posits that over time there are IQ gains such that if
a sample is re-tested on a previous test then the mean is no longer
100 (Flynn Effect, n.d.). It is also known that the standard deviation
is 15. Suppose a researcher re-test a sample of 52 persons with a
previous test and the mean is now 120.
a) Is there evidence to substantiate the Flynn effect at the 1%
significance level?
b) If there is an increase in the average, what are factors that could give
rise to this?

Answer by ewatrrr(24785) (Show Source):
You can put this solution on YOUR website!

z = 20/(15/sqrt(52)) = 20/2.08 = 9.6148
at the 1% significance level: critical value 2.576
Is there evidence to substantiate the Flynn effect at the 1% significance level?
Yes, re-test demonstrates significantly(according to the test statistic)that there is an increase in average score.
......
b) familiarity with the test format etc...