Lecture #6 -

Question 1

The “New Statistics” is…

Answer 1

• Effect size, confidence intervals, and meta analysis.

Question 2

Point Estimate:

Answer 2

• A summary statistic from a sample that is just one number used as an estimate of the population parameter.

Question 3

Interval Estimate (Margin Of Error OR CI)

Answer 3

• Is based on a sample statistic and provides a range of plausible values for the population parameter.

Question 4

Confidence Interval (CI):

Answer 4

• An interval estimate based on a sample statistic; it includes the population (parameter) a certain percentage of the time if the same population is sampled from repeatedly.
• Is centred around the mean of the sample
• Includes range around the mean when margin of error is added and subtracted.
• Confirms findings of hypothesis testing and adds more detail.

Question 5

Calculating Confidence Intervals With The z Distribution Steps:

Answer 5

Step #1 - Draw a picture of a distribution that will include the CI.
Step #2 - Indicate the bounds of the CI on the drawing.
Step #3 - Determine the z statistics that fall at each line marking the middle 95%.
Step #4 - Turn the z statistics back into raw means.

Question 6

What Is Effect Size?

Answer 6

• Describes the size of a difference that is unaffected by sample size.
• allows standardization across studies
• tells how much two populations do not overlap.

Question 7

Cohen’s d:

Answer 7

• A measure of effect size that expresses the difference between two means in terms of standard deviation.

Question 8

Meta Analysis:

Answer 8

• A study that involves the calculation of a mean effect size from the individual effect sizes of more than one study.

Question 9

Steps In Meta Analysis:

Answer 9

1) Select the topic of interest and decide exactly how to proceed.
2) Locate every study that meets criteria.
3) Calculate an effect size for every study
4) Calculate statistics

Question 10

Statistical Power:

Answer 10

• Likelihood we will reject the null hypothesis, given that the null hypothesis is false.

Question 11

Statistical Power Equation:

Answer 11

• Power = Effect Size x Sample Size

Question 12

Factors That Affect Statistical Power:

Answer 12

1) Increasing alpha
2) turning a two tailed hypothesis into a one tailed hypothesis.
3) Increasing N (number of subjects)
4) Exaggerating the mean difference between levels of the independent variable
5) Decrease variability within groups

Question 13

Sample Size Planning:

Answer 13

• Plan sample sizes in advance, before the start of data collection.
• use a power calculator to plan sample size based on the expected effect size before the study begins.
• Correct the expected effect size downward because of the bias toward publishing only significant effects.