Question

1. Numerous studies have shown that IQ scores have been increasing, generation by generation, for years. The increase is called the Flynn Effect, and the data indicate that the increase appears to be about 7 points per decade. To demonstrate this phenomenon, a researcher obtains an IQ test that was written in 1980. At the time the test was prepared, it was standardized to produce a population mean of µ = 100 and σ = 15. The researcher administers the test to a random sample of n = 16 of today’s high school students and obtains a sample mean IQ of M = 120. Is this result sufficient to conclude that today’s sample scored significantly higher than would be expected from a population with µ = 100? Use a one-tailed test with α = .01. If significant, determine the effect size through Cohen’s d. Note that Cohen’s d = M - µ*

Answer 1

Claim: Today's sample scored significantly higher than would be expected from a population with µ = 100.

The null and alternative hypothesis is

Level of significance = 0.01

Sample size = n = 16

Sample mean = = 120

Population standard deviation = = 15

Test statistic is

Level of significance = 0.01

Critical value = 2.32 ( Using z table)

Critical value < Test statistic we reject the null hypothesis.

Conclusion:Today's sample scored significantly higher than would be expected from a population with µ = 100.