convenience sample
choosing individuals who are easiest to reach
random sample
method of selecting from a population in which each person has an equal probability of being selected
random assignment
being randomly assigned to a given experimental group to reduce bias
sample size
the number of individuals in a sample (depends on the variability of the population)
golden rule of sampling
sample must be similar/match population as close as possible
self-selection
a form of sampling bias that occurs when a sample contains only people who volunteer to participate
external validity
the extent to which the results of a study can be generalized to other situations and to other people
homogenous population
population with little standard deviation/variability
Sample
a subset of the population
Population
entire group that has something in common
Conditional Probability
the probability of an event ( A ), given that another ( B ) has already occurred.
Probability
# of successes/# of total trials
Law of Large Numbers
over time, actual outcomes will tend to mirror predicted outcomes
Null Hypothesis (H0)
NO relationship between or among variables
Alternate Hypothesis (Ha)
there IS a relationship among variables
?
odds of making a Type I error/chance of accepting Ha & being wrong
?
odds of making a Type II error
Power
chance of accepting Ha & being right