Exam II Flashcards
Dependent Variable
what is being measured
Independent Variable
what explains variability in the DV, assumed to influence DV directly and indirectly, also referred to as predictor, or explanatory factor
Confounding variable
The effect of X on Y, after controlling for Z…
Here, Z is a confounder
Quantitative Variables
Data expressed in numbers where the numbers have numerical meaning (ex: age, weight, temperature, RBC count)
Qualitative Variables
Qualitative variables are those having exact values that can fall into number of separate categories with no possible intermediate levels
Nominal Variables
Unordered
Can be dichotomous (aka binary or binomial)
2 categories
-E.G. infected vs. not infected, injured vs. non-injured
…or multichotomous (aka multinomial)
-More than 2 categories
-E.G. blood type, college major
Ordinal Variables
Ordered
Can be Score (e.g. birth order)
…Categorical (e.g. social class)
…or Rank
May refer to specific rank within a dataset, as opposed to “score”, which is not limited to a dataset
Sampling
Experiments are performed on a representative samples, not whole populations
Type I Error
No population effect exists, but a sample effect is detected (false positive)
Type II error
Population effect exists, but no effect is detected in sample (false negative)
Probability sampling
randomly draw from sample frame
Nonprobability sampling
nonrandomly draw from sample frame
Sampling frame
those who have a real chance of being selected for the sample
Random sampling
every potential individual in the sampling frame has an equal chance of being selected
Systematic random sampling
every ith individual out of the entire list is selected
Stratified random sampling
individual members of the sampling frame are divided into groups (“strata”) based on specific characteristics
Cluster random sampling
sampling frame itself is divided into groups and then clusters are randomly selected
Convenience sampling
subjects selected based on ease of recruitment
Purposive sampling
subjects recruited from a predetermined group
Internal validity
concerns a study’s experimental design
External validity
are study results generalizable to the real world?
Ecological validity
refers to the applicability of research studies in context-specific environments
Content validity (face validity)
outcome comprehensiveness
Criterion validity
outcome comparison