Statistics in Psychology UTA (Hernandes)

1. D1. Define and give examples of the 4 levels of measurement: nominal, ordinal, interval, and ratio.

2. Define & explain sampling error. Explain it with your own hypothetical example.

3. Explain the difference between descriptive and inferential statistics. What is the purpose
of each? Come up with your own example of each.

4. What is a sample? Population?

a. What does a parameter refer to? A statistic?

5. For two variables to be correlated, both variables should be __________

6. Give examples of two variables that would be:
... positively correlated
... negatively correlated
... zero correlation.

7. Explain correlation coefficient (r). What does it mean if the coefficient is positive vs
negative? What does it mean if the absolute value of the coefficient is higher vs lower?
Make some sketches – approximately what would these correlations look like as a
scatterplot with a line of best fit? R=-.8... r=-.3... r=.01... r=.3... r=.9

8. What is an illusory correlation? What is a third-variable problem? Give an example. Try
to create your own examples.

9. What are independent and dependent variables?

10. Give an example of a true-experimental design. What are some key features of a true
experimental design? Explain why/how true-experimental design can determine
causation.

11. What is a “quasi-experimental design?” Give an example.

12. What is simple random sampling? Convenience sampling? Stratified sampling?

13. Describe what is sampling error and what can cause it.

14. What do these symbols mean: n... r... M...x̄... ... SD... ...
.... z...

15. What do the following types of graphs help display?
a. Line graphs
b. Bar graphs
c. Histograms
d. Scatterplots
e. Box plots
f. Stem-and-leaf displays
g. Frequency polygons

16. What is denominator neglect? Why does it happen?

17. When should you use mean vs median as your measure of central tendency?

18. What is variability? What could influence the amount of variability in a set of scores?
a.

19. What is a z-score? How do you interpret them? When can z-scores be used? What are the
benefits of using z-scores?

20. What is the 68-95-99.7 approximation? When can it be used?

21. What is a Normal Distribution?
a. What are the characteristics of a normal distribution?

22. What is positive skew? What is negative skew? How can you tell which is which?
a. How do ceiling effects and floor effects relate to skew?
b. How do the mean, median, mode compare to each other in each type of skew?

23. What are the measures of variability? (range, standard deviation, variance)
a. When and why are they used/reported?

24. What is a confound? How does it interfere with the results of a study?

25. What is the effect of noise variables on variability?

26. How do you calculate variance? SD? (think of they are conceptually calculated)