Suppose a developmental psychologist is interested in theeffects of fluoride in water on children’s heights. She measuresthe heights of a random sample (N = 21) of 12-year old children wholive in an area with a very high level of natural fluorides in thewater. She is interested in comparing the average height of thesechildren with the known population mean height, which she takesfrom published growth tables (µ = 58.0 inches for 12-yearolds). The data file ‘fluoride-spring2020.csv’gives her raw sample data. Answer the following questions. You willwant to take some of your answers from spss.

Spps file data:

60
54
65
62
59
57
52
69
61
63
66
62
50
70
66
53
66
63
65
59
49

.(3 pts) If the sample of 21 children was unbiased, and the samplesize was made much larger and remained unbiased, what would youpredict about the decision about the null hypothesis in that case?(That is, would you expect to reject the null or fail to rejectit?) Explain why or why not.

J. (2 pts) Imagine that the sample size got muchlarger (as in sub-question h), but that the sample mean andstandard deviation remained unchanged. In that case, what wouldhappen to the value of Cohen’s d?

K. (3 pts) Calculate the 95%confidence interval (CI) for estimating the population mean, basedon the sample. (Do this by hand; the option to find the CI in JASPis for the difference between the two means, not the estimate ofthe population mean based on the sample data.)   

L. (2 pts) Describe why it makessense that the number 58.0 either should or should not be includedin the 95% CI, based on your decision about H₀.In other words, how does knowing the CI complement the result fromtesting the null hypothesis?