Basics
What is the difference between independent and dependent variables?
IV is manipulated/predictor; DV is measured/outcome.
What does variability tell us?
How spread out scores are/ our 'spread'
What's H₀ ?
No effect or no difference.
null hypothesis
You want to know how far one raw score is from the mean in SD units.
z-score: z = (X − μ) / σ
3+ separate groups, one IV
One-way between-subjects ANOVA
One way stands for(?)
What is the highest score minus the lowest score?
Range
What does standard deviation measure?
Average spread from the mean.
What are the four steps of hypothesis testing?
State hypotheses, set criteria, compute test statistic, make decision.
You want to test (1) sample mean against a known population mean, and σ is known.
One-sample z-test
(POPULATION SD BEING KNOWN = one-sample-z-test)
3+ related/repeated groups, one IV
One-way within-subjects ANOVA / repeated-measures ANOVA
What is the difference between a population and a sample?
A population is the whole group; a sample is part of it.
What is the IQR formula?
Q3 − Q1
What is a Type I error?
Rejecting a true null hypothesis
(Telling a man he's pregnant~)
You want to test one sample mean against a population mean, but σ is unknown.
One-sample t-test
(IF) ANOVA is significant, we need to know which groups differ --> so we do...
Post hoc test, usually Tukey’s HSD
Name the four scales of measurement
Nominal, ordinal, interval, ratio
Why do we use n − 1 for sample variance?
To 'correct sample bias' (reduces the certianty, which is important because it's a sample and could be skewed
If p < α, what happens?
Reject H₀
EXAMPLE:
.02<.05
--> Should be over that 'five' percent chance (.06-1.00)
You want to compare two separate groups, like men vs women or control vs treatment.
Independent-samples t-test
2 quantitative variables, relationship
Correlation, usually Pearson’s r
What's the difference between descriptive statistics vs inferential statistics?
- Descriptive statistics summarize/describe features of a dataset (sample or population)
- Inferential statistics use sample data to make generalizations/predictions about a larger population.
What is standard error?
How much sample means vary from the population mean.
SAMPLE standard deveation / √sample size
(s)/√n
t-tests and z-tests
What does statistical power mean?
The probability of correctly rejecting a false null.
You want to compare the same people twice, like before vs after treatment.
Related-samples / paired-samples t-test
Predict one variable from another
Linear regression