PSYC232 Test 2, Week 7 Flashcards
What type of research question involves an independent samples t-test?
A research question that involves two groups being different, with one variable being categorical and one variable being continuous.
What is the minimum sample size for an independent samples t-test?
30 people.
What do descriptive statistics tell you in an independent samples t-test?
They tell you which group is bigger than the other if there is a statistically significant difference (check for higher mean).
What is Levene’s Test used for?
Comparing the variance of groups to see if the variances are statistically different. If not significant, continue with the test; if significant, use Welch’s test instead of Student’s.
What does the Student’s t-test compare?
It compares the means of both groups, calculates the effect size, and determines the mean difference between the two groups. Cohen’s d is used as the effect size.
What are the assumptions of an independent samples Student’s t-test?
- Each measurement in the sample is independent.
- The variables are normally distributed (larger samples are good).
- Variances of the two groups are relatively equal.
What does a significant result in Levene’s Test indicate?
It indicates that we should not assume equal variances (p < .05).
What does a significant result in the Student’s t-test indicate?
It indicates that there is a significant difference between the means of the two groups, leading to the rejection of the null hypothesis.
What are the approximate guidelines for Cohen’s d effect size?
Small: 0.2
Medium: 0.5
Large: 0.8
What is the standard error of the mean?
A measure of how close the sample mean probably is to the actual population mean. It is graphically displayed by error bars on an APA graph.
What is the formula for typical error bars?
Standard Error x 1.96
What should you keep in mind about significant differences?
Significant differences do not mean large, always-replicated, or practically meaningful differences.
What are the assumptions and use of Chi-Square tests?
Chi-Square tests are used to test the relationship or association between two categorical variables. Assumptions include:
- Measurements are independent.
- There are at least five measurements in each cell.
How do you interpret the results of Chi-Square tests?
Chi-Square tests examine whether the proportions/percentages across groups are significantly different. A significant p-value indicates a statistically meaningful difference.
How do you select the appropriate statistical test to measure the relationship between two variables?
- Continuous differences between two groups: Independent samples t-test. (categorical/continuous always a t-test)
- Relationship between two continuous variables: Correlation.
- Relationship between categorical variables: Chi-Square test. (look for word likelihood except for percentages)
Why should we be cautious when finding a statistical relationship?
- Correlation does not equal causation.
- A third variable may cause the relationship.
- The relationship may be due to outliers or random chance.
What is the relationship between feeling able to influence someone and perceiving that they can influence you?
This relationship is between two continuous variables and should be tested using a correlation.
What test should be used to examine the relationship between thinking the class survey took a short vs. long time and the personality trait of agreeableness?
Use a t-test, as it involves a categorical and a continuous variable.
What test should be used to examine the relationship between having the tendency to cry sometimes and political orientation?
Use a Chi-Square test, as both variables are categorical.
What test should be used to examine the relationship between entitlement (Likert scale) and year of PSYC232?
Use a t-test, as it involves a continuous variable and a categorical variable.
