Variable
Attribute that can take different values
Independent variable
Variable influenced by experimenter
Dependent variable
Variable that is being tested to see if independent has an effect
Qualitative data
Information in verbal or narrative form
Quantitative data
Information given in numerical form
Sample
A limited number of observations from a set with attributes relevant to the research question
Population
The entire set
Negative correlation
When one variable increases the other decreases
Positive correlation
Increase in one variable is associated with an increase in another variable
Mean
Measure of central tendency (average)
Median
The value that divides a distribution in two (the 50th percentile)
Mode
The most frequently occurring value
Normal distribution
Distribution that is unimodal and symmetrical around its mean (bell curve)
Hypothesis testing
Use statistical inference to test if variables are related
Null hypothesis
States that the variables in question are not related
Snowballing sampling
Subjects tend to recruit their friends
Correlational study
Study designed to see if two or more variables are related; does not give cause and effect
Case study
Study that investigates a single person or a small group
Ethnography
Holistic study on the culture of a group of people
Observational study
Study that uses a sample to draw conclusions about a population; researcher does not control an independent variable or manipulate the environment
Case-control study
Study that compares a group of people with a particular outcome against a group of people who do not have that outcome
Cross-sectional study
Study that draws from a population at a single point in time
Longitudinal study
Study that gathers the same data from a set of individuals at many points in time
Experimental study
Researchers actually manipulate the groups or environment study; establish cause and effect
Randomized controlled trial
Experimental medical study where patients are randomly assigned to receive different treatments
Prospective study
The outcome of interest lies in the future
Retrospective study
The outcome of interest has already happened
Mixed-methods study
Study that uses quantitative and qualitative data
Hawthorne effect
A change in the behavior of study subjects in response to their knowledge of being observed (observer bias)
Operationalization
The process of establishing parameters designed for indirect measurement of a phenomenon that may not be readily directly measurable
Operational definitions
Clear definitions of terms in a process or procedure to be used in acquiring data on the properties of a phenomenon, group, or object
Survey-response bias
Tendency for respondents to written or oral survey to offer false, dishonest, or misleading answers
Reliability
Measure is reliable if the same result can be obtained over repeated measurements
Validity
Measure is valid if it actually measures what it purports to measure
External validity
General applicability of a study's results to other similar situations
Internal validity
Validity of a given study's evidence toward supporting its conclusion
Quantitative methods
Focus on producing data in numbers for use in statistical tests
Qualitative methods
Methods focusing on producing textual descriptions
Ethnographic methods
Participatory field research and informant interviews
Survey methods
Uses a questionnaire