Research Methodology I: Unit 2 Exam Review

Operational definition

the specific ways in which a concept of interest is measured or manipulated as a variable in a study

Conceptual definition

a researchers definition of a variable at the theoretical level ("also called “construct”)

self-report measure

a method of measuring a variable in which people answer questions about themselves in a questionnaire or interview

observational measure

a method of measuring a variable by recording observable behaviors or physical traces of behavior

physiological measurement

a method of measuring a variable by recording biological data

Four scales of measurement (NOIR)

nominal (categorical), ordinal scale, interval scale, ratio scale

ordinal scale

levels represent a ranked order (rank order)

interval scale

variable in which subsequent numerals represent equal distances, but there is no true zero

ratio scale

variable in which numerals represent equal distances and zero represents “none” of the variables being measured (true zero)

Quantitative vs. qualitative research

a variable whose values can be recorded as meaningful numbers

vs

a variable whose levels are categories

Three types of reliability

test-retest

interrater

internal

test-retest reliability

the consistency every time a measure is used

interrater reliability

the degree to which two or more coders or observers give consistent ratings of a set of targets

internal reliability

in a measure that contains several items, the consistency in a pattern of answers, no matter how a question is phrased

Five types of construct validity

face, content, convergent, discriminant, criterion

Types of questions (forced-choice/close-ended questions vs. open-ended questions; likert-scale questions)

close-ended

open-ended

likert-scale

social desirability bias

the tendency of survey respondents to answer questions in a manner that aligns with social norms and presents them in a favorable light

observer bias

occurs when observer expectations influence the interpretation of participant behaviors or the outcome of the study

observer effects

a change in the behavior of study participants in the direction of observer expectations

population

a larger group from which a sample is drawn; the group to which a study’s conclusions are intended to be applied

sample

the group of subjects used in a study; a subset of the population of interest

external validity

an indication of how well the results of a study generalize to, or represent, individuals or contexts besides those in the study

statistical validity

the extent to which statistical conclusions derived from a study are accurate and reasonable

biased sample

unrepresentative

a sample in which some members of the population of interest are systematically left out, and therefore the results cannot generalize to the population of interest

unbiased sample

representative

a sample in which all members of the population are equally likely to be included, and therefore the results can be generalized to the population of interest

the six techniques of probability sampling

1. simple random sampling

2. systematic sampling

3. cluster sampling

4. multistage sampling

5. stratified sampling

6. oversampling

The four techniques of nonprobability sampling

1. convenience sampling

2. purposive sampling

3. snowball sampling

4. quota sampling

bivariate correlation

an association that involves exactly two variables

random sampling vs. random assignment

the sample is chosen completely at random from the population of interest → external validity

used only in experimental designs when researchers want to assign people to groups at random → internal validity

scatterplots vs bar graphs

helps describe associations between two quantitative variables

helps describe the association between categorical data

interrogating statistical validity of association claims

• effect size: describes the strength of the relationship between variables (larger = more important)

• confidence interval: how researchers convey precision → 95% CI (if a study was repeated multiple times, 95% of the CIs will contain the true population)

• if a confidence interval does not contain zero, it can be considered statistically significant

• the larger the sample, the more precise the confidence interval

moderating variables

a variable that, depending on its level, changes the relationship between two other variables

multiple regression

a statistical technique that computes the relationship between a predictor variable and a criterion variable, controlling for other predictor variables

longitudinal studies

a study in which the same variables are measured in the same people at different points in time

pattern and parsimony

a variety of correlational studies that all point to a single, causal effect (simplest explanation)

mediating variables

a variable that helps explain the relationship between two other variables

criterion variable vs predictor variable

the variable researchers want to understand or predict (dependent variable)

the variable that is used to explain variance in the criterion variable (independent variable)