Descriptive vs. Inferential
What branch of statistics focuses on summarizing information like averages and graphs?
Descriptive statistics.
What kind of variable is “favorite music genre”?
Nominal variable.
What do we call the most representative value in a set of scores?
Measure of central tendency.
In a distribution of Z scores, what is always the mean value?
0.
What is the name of the starting assumption that there is no difference or effect?
Null hypothesis (H0).
What branch of statistics allows researchers to draw conclusions about a population using data from a sample?
Inferential statistics.
A number assigned to a single participant on a test is called their what?
Score.
In a distribution with a long tail on the left, which measure of central tendency tends to be pulled downward?
Mean (M).
What Z score corresponds to being one standard deviation above the mean?
+1.
What kind of error occurs when a researcher concludes there is an effect when in reality there is none?
Type I error.
A psychologist collects survey responses and makes a frequency table to display them. Which branch of statistics is this?
What is descriptive statistics.
What kind of graph is most useful to show the shape of a distribution of scores?
Histogram.
What does variance represent in relation to scores?
The average of the squared deviations from the mean (SS).
A student takes two entrance exams; on which exam did the student perform better relative to peers?
Exam A: Student’s score = 82; Group mean = 70; SD = 8
Exam B: Student’s score = 560; Group mean = 540; SD = 20
Exam A.
If a psychologist predicts a treatment could make symptoms either better or worse, what kind of test should they use?
Two-tailed test.
A researcher tests whether students at one university score differently on stress measures compared to all college students nationwide. Which branch of statistics is being used?
Inferential statistics.
What type of variable is “finishing place in a marathon” (1st, 2nd, 3rd)?
Ordinal variable.
Which statistic tells us how far scores, on average, differ from the mean in the original units of measurement?
Standard deviation (SD).
Roughly what percentage of scores fall between the mean and one standard deviation above it in a normal distribution?
About 34%
What does effect size tell researchers about research results?
The magnitude or strength of the effect.
Why are inferential statistics considered essential in psychological research?
They allow researchers to test hypotheses and generalize findings beyond the studied sample.
How is a ratio scale different from an interval scale?
interval scale - equal intervals but no true zero
ratio scale - having equal intervals with a true zero
Which set of numbers would show greater variability:
Set A: 50, 51, 52, 53
Set B: 5, 25, 60, 95
Set B.
If a student’s score is in the top 2% of a normal distribution, what Z score do they need to have at minimum?
About +2.00.
What is statistical power, and why does it matter?
Power is the probability of detecting a real effect when it exists; it matters because higher power reduces the chance of missing true effects (also so you don't waste your time!)