12. If the sample mean is 57.2, with an upper limit to the confidence interval of 62.74, what is the lower limit?
a. 5.54
b. 51.66
c. 53.46
d. 57.20
13. Why are effect sizes rather than test statistics used when comparing study results?
a. Effect sizes, unlike test statistics, are not affected by sample size and thus ensure a fair comparison.
b. It is easier to average effect size than it is to average test statistics.
c. Effect sizes are based on standard error, while test statistics are based on standard deviation.
d. Effect sizes, unlike test statistics, account for sample size, thereby ensuring an accurate comparison.
14. The statistical convention for the minimal acceptable power is:
a. 0.95.
b. 0.90.
c. 0.80.
d. 0.75.
15. Imagine that a study of memory and aging finds that younger participants correctly recall 58% of studied
words and older participants correctly recall 41% of studied words; the size of this effect is Cohen's $d = 0.48$.
According to Cohen's conventions for interpreting $d$, this effect is:
a. small.
b. medium.
c. large.
d. so small as to be considered virtually no effect.
16. Increasing sample size does NOT:
a. increase statistical power.
b. decrease standard error.
c. increase the magnitude of the test statistic.
d. decrease statistical power.
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