Q1) In a completed study there is a known population with a normal distribution. Population M = 122, and Population SD =8. What is the estimated effect size if a sample given an experimental procedure has a mean of (a) 100, (b) 110 (c) 120 (d) 130 and (e) 140?

i) Show your calculations for each part

ii) For each part, also indicate whether the effect is approximately small, medium, or large.

a)

b)

c)

d

e)

Q2 Here is information about several versions of a planned study, each involving a single sample. Calculated the predicted effect size for each study.

	Population 2	Predicted
Study	M	SD	Population 1 M	Effect Size
a	90	2	91
b	90	1	91
c	90	2	92
d	90	2	94
e	90	2	86

3. How does each of the following affect the power of a planned study?

(a) A larger predicted difference between the means of the population

(b) A larger population standard deviation

(c) A larger Sample size

(d) Using a more extreme significance level (e.g. p < .01 instead of p < .05)

(e) Using a two-tailed test instead of a one tailed test.

4. What is meant by effect size? (Write your answer for a lay person and include a drawing) (5 marks)

5. What is meant by the statistical power of an experiment? (Write your answer in a manner that a person that is not skilled in statistics could understand and include a drawing) (5 marks)