Chapter 8 Part 2 Flashcards
What is effect size?
Quantifying size diff between two groups to judge the significance of the results
What is an issue with hypothesis testing?
Only using critical/p-values without considering effect size and its effect on results
What is more likely to produce a significant sample size?
Small absolute difference between two means > more likely to be statistically significant with large sample than small
What are two ways to explain the difference between the two groups being compared?
Absolute diff between group means, standardized diff btw n group means
What is absolute effect size?
Diff between means expressed in the distributions of measurements
When is absolute effect size useful?
When variables have intrinsic and well-understood meanings
What is a downside to absolute effect size?
comparing two raw scores w/o thinking of distribution spread
What is standardized effect size?
Diff between group means
When is standardized effect size useful?
measurements have no intrinsic meaning, different scales of measurement
What does the standardized effect size serve the basis for?
Comparing differences across studies, used extensively in post-hoc meta-analyses
What is the standardized effect size equation mean?
difference between means is divided by the standard deviation to yield the standardized mean difference between groups
What does the standardized mean difference provide?
common ground for comparison
Why does the standard deviation need to be included in the calculation?
To correct for differences in the spread
When Cohen’s d be used?
When comparing mean scores of two groups
What is cohen’s d simply?
Difference between the two group means divided by the average of their standard deviations
How is cohen’s d arranged by size?
.2 is small, .5 is medium, and a .8 is large
How is cohen’s d calculated?
nothing more than the difference between two group means divided by their pooled standard deviations
An effect size of zero would indicate __________.
No effect of IV
Cohen’s d is used to calculate a ____ effect size….
standardized
What is a Type 1 error?
Rejecting the null hypothesis when it is in fact true
What does the level of significance of a statistical test also set?
The maximum probability of making a Type 1 error
In the case of errors what does an alpha also determine?
Probability of making a type 1 error
What is a type 2 error?
probability of rejecting the null when It is in fact false
What is the relationship between the type 1 and the type 2?
As the probability of the type 2 increases the probability of a type 1 decreases
What is the type 2 inversely related to?
level of significance
What does the type 2 error depend on?
Population mean
What is the correct decision probability for a type 1?
1-a
What is the correct decision probability for a type 2?
1-b