midterm Flashcards
Cluster sample
a sample that is used when no list of elements exist
Convenience sample
sample is simply convenient to the researcher
Disproportionate sample
when elements are overrepresented or underrepresented
Element
referred to as case and is about which information is collected (unit of analysis)
Sampling unit
like an element, but can be a cluster or group
Sample bias
bias occurring whenever some (key) elements of a pop. are systematically excluded from a sample
Nonprobability sample
each element in the total population has an unknown probability of being selected
Snowball sampling
respondents identify others who might qualify for inclusion in the study
Purposive sampling
with much discretion from the researcher, the goal is to study a “diverse” and (usually) limited number of observations from the population without a requirement for representativeness
probability sample
elements are divided into groups based on one or more characteristic
Simple random sample
Each element has an equal chance of being selected
Stratified sample
A probability sample in which elements are divided into groups based on one or more characteristic
stratum
subgroup that shares one or more characteristics
Cause of effects approach
Starts with outcomes and works backwards to the cause
Classical randomized experiment
random assignment of subjects between control and experimental group with a pretest and posttest
Control group
does not receive treatment
Correlation
a statement that two things are systematically related
Demand characteristics
aspects of the research situation that cause participants to guess at the investigator’s goals and adjust their behavior or opinions accordingly
Effects of cause approach
Starts with a potential cause and works forward to examine its impact on the outcome
Experimental effect (aka program impact)
the portion of an outcome change that can be attributed uniquely to a program
Experimental mortality
the differential loss of subjects from experimental and control groups that affect the equivalency of groups
External Validity
The extent to which the results of a study can be generalized across populations, times, and settings