Ch. 7 Statistical Issues in Research Planning and Evaluation

What are three (3) things a researcher could do to increase the power if the study were done a second time?

1. Relationship among alpha 2. Sample Size 3. Effect Size (ES)

A null hypothesis is...

A statistical hypothesis that assumes that there is no difference among the effects of treatments

A researcher decided to use an alpha of .01 and a power of .80. To determine the needed sample size the researcher must ascertain the expected

Effect Size (ES)

A measure of meaningfulness that expresses the difference between the experimental and control group in standard deviation units is the

Effect size (ES)

Explain what is meant by the statement that a statistical test may be statistically significant but not meaningful. Give an example of such circumstance.

I can cook a turkey for 10 minutes, but it's not meaningful to me because I don't like turkey

If a researcher finds a small difference in average test scores between a large sample (over 700) of experimental participants and a large sample (same size) of control participants, it is very likely that the difference is...

Statistically significant but does not have a high degree of meaningfulness

When a researcher states that a result is significant, this means that...

The result is unlikely to be a chance occurrence

Which hypothesis is stated in the null form?

There is no difference between the vocab scores of average- and high-ability students

When a researcher claims that there is a difference between treatments (i.e., rejects the null hypothesis) when there really is no difference, what type of error is this?

Type 1 Error

When an experimenter states that the level of significance is the .05 level, he is setting the probability of committing which type of error?

Type 1 Error

If the researcher fails to reject the null hypothesis when there really is a difference, this is an example of a...

Type 2 Error