Exam 2 Flashcards
what is randomization?
ensures all groups are equivalent before the IV is given. controls for individual difference variability
what are the two components of randomization?
- random sample: each possible subject has an equal chance of being selected
- random assignment: once selected, each subject has an equal chance of being placed into any group
in order for randomization to work, what must be met?
- law of large numbers: as sample size increases, sampling variance increases
- central limit theorem: need a minimum of n = 30 subjects for each group
what type of variance is within groups variance?
bad variance = error due to individual differences, extraneous variables, and random error
what type of variance is between groups variance?
good variance
between groups variance is variance due to the ____ and is found in the _______ of the test statistic
between groups variance is variance due to the IV and is found in the NUMERATOR of the test statistic
within groups variance is variance due to the ____ and is found in the _______ of the test statistic
within groups variance is variance due to ERROR and is found in the DENOMINATOR of the test statistic
what is a significance (alpha) level?
the risk… max alpha = .05
what is the max min con principle?
we want to maximize variance due to the IV, minimize error variance due to individual differences, and control variance due to random error or extraneous variables (bad variance)
A type 1 error occurs when we _____ H0 when H0 was really _____
A type 1 error occurs when we REJECT H0 when H0 was really true
A type 2 error occurs when we _____ H0 when H0 was really _____
A type 2 error occurs when we ACCEPT H0 when H0 was really false
when does “no error” occur?
when we accept H0 and it was true
when does “power” occur?
when we reject H0 and it was false
if each subject receives only ONE level of the IV it is called…?
BETWEEN subjects design
if each subject receives ALL levels of the IV it is called…?
WITHIN subjects design
