Week 3 Flashcards
What is a t-statistical test?
Statistical method to decide whether an observed difference in sample scores represents a “real” difference in the population…. vs. just sampling error
How many groups are in a t-test?
2 groups
2 groups is another way of saying…?
2 levels of 1 IV
What does a t-test do?
Finds the difference between group means divided by the variability within the groups( standard error of the mean difference)
The error in a standard error refers to…?
All sources of variability within a set of data
that cannot be explained by the independent variable.
A within group variability with no variability is known as being ___ ?
A within group variability with no variability is known as being definitely different ?
A within group variability with little bit of variability is known as ___ ?
A within group variability with little bit of variability is known as probably different
A within group variability with larger amounts of variability is known as ___
A within group variability with larger amounts of variability is known as maybe not different
When the variability between groups are not necessarily the same, it is called…?
When the variability between groups are not necessarily the same, it is called a differing variance
What is a parametric statistics?
A branch of statistics which assumes that sample data comes from a population that follows a probability distribution based on a fixed set of parameters.
What are some examples of a parametric statistics?
- t-Tests
- ANOVA
- ANCOVA
- Regression
- Correlation
What are the basic assumptions for all parametric test?
- Samples are randomly drawn from populations
- Population is normally distributed
- Homogeneity of variance (roughly)
- Data from ratio or interval (i.e. continuous) scales
What rarely happens, but one still needs to be careful with when samples are randomly drawn from populations?
Generalization
What are the ways to test if the population is normally distributed?
- Statistically
- Graphically
- Common sense
When is the homogeneity of variance especially important?
With unequal group sizes
How is the homogeneity of variance tested?
Statistically
What statistical test is used for the t-test?
Levene’s test
What are the statistical hypotheses for the null hypothesis for a two-level design?
- The two population means are equal
- The hypothesis can be in a nondirectional format (not equal)
- Directional format (one is greater than the other)
A two-tailed test uses a ___ hypothesis
A two-tailed test uses a nondirectional hypothesis
A one-tailed test uses a ___ hypothesis
A one-tailed test uses a directional hypothesis
A two tailed test has ___ statistical power compared to the one tailed test
A two tailed test has less statistical power compared to the one tailed test
What are the two types of t-test?
- Independent/unpaired t-test
- Paired t-test
What happens in an unpaired(independent) t-test?
Testing to see if there is a difference between 2 groups
What kind of design is found in an unpaired t-test?
- Pretest-posttest design (compare change scores)
- Posttest only design
What happens in a paired(dependent) t-test?
Testing to see if there is a difference between conditions in the same person
What kind of design is found in a paired t-test?
- Difference scores or pretest-posttest
- Repeated measures design
A repeated measures factor is an example of a ___
A repeated measures factor is an example of a within-subjects factor
A non-repeated measures factor is an example of a ____ factor
A non-repeated measures factor is an example of a between-subjects factor
