Glossary of Research TermsWritten by
Ari Julianto
Abstract----a brief summary of the research study.
Analysis---the process of synthesizing data to answer the research question.
Alpha---in tests of statistical significance, the alpha level indicates the Probability of committing a Type I error; in estimates of internal consistency, a reliability coefficient, as in Cronbach alpha.
Analysis of variance---a statistical test for comparing mean scores among 3 or more groups.
Beta---in statistical testing, the beta is the probability of a type II error; in multiple regressions, the standardized coefficients indicating the relative weights of the independent variables.
Bias---any influence that can change the results of a study
Case Study---a study design that provides an in-depth review of a single subject or case.
Causal relationship---a relationship between 2 variables in which the presence or absence of one variable determines the presence or absence of the other.
Chi-square test---a nonparametric statistical test used to determine relationships between two nominal level variables.
Cluster sampling---selecting a random sample from clustered groups.
Coefficient alpha (Cronbach alpha) ---a reliability index that estimates the internal consistency of a measure with several items of sub-parts.
Conceptual map---a diagram representing the relationship of variables.
Concurrent validity---the degree to which scores on an instrument are correlated with some external criterion, measured at the same time.
Confidence interval---a range of values that a parameter is estimated to fall within.
Confounding variable---a variable that might affect the dependent variable, also termed “extraneous variable” subject.
Construct validity---the degree to which an instrument measures the construct intended.
Content analysis---the process of organizing narrative qualitative information according to themes and concepts.
Control group---subjects in a research study who do not receive the experimental treatment.
Convergent validity---a type of validity that reflects the degree to which scores from an instrument resemble scores from a different measure of the construct.
Correlation coefficient---an index that reflects the degree of relationship between 2 variables. A perfect positive relationship + 1, no relationship is 0, and – 1 is a perfect negative relationship.
Criterion validity---the degree to which scores on an instrument are correlated with some external criterion.
Cronbach alpha---a reliability index that reflects the internal consistency of a measure.
Cross-sectional study---a study design that collects data at a single point in time for the purpose of inferring trends over time.
Data cleaning---the process of trying to find errors in the data set.
Degrees of freedom---a concept used with statistical tests that refers to the number of sample values that are free to vary. In a sample, all but one value is free to vary, and the degrees of freedom is often N-1.
Descriptive study---a study that defines or describes a population or phenomenon.
Descriptive statistics---methods used to describe or summarize the characteristics of data in a sample.
Dependent variable---the outcome variable of interest.
Dichotomous variable---a variable with only 2 categories.
Effect size---a statistical term of the magnitude of the relationship between 2 variables.
Experimental group---subjects in a research study who receive the experimental treatment or intervention.
Exploratory study---a type of study design used to explore or gain insights into a phenomenon.
Ex post facto---a type of research design that studies something after it has occurred.
Experiment--- a research study in which the independent variables are manipulated and subjects are randomly assigned to different conditions.
External validity---refers to how representative the results of the study are (generalizability).
Face validity---the degree to which a test appears to measure a concept based on the judgment by experts.
Factor analysis---a statistical procedure for reducing a large set of variables into smaller sets of related variables.
Focused interview---an interview that is partially structures or semi-structures.
Frequency distribution---a display of data values from the lowest of the highest, along with a count of the number of times each value occurred.
Grounded theory---a method used in qualitative research to develop categories of theories and propositions about their relationships from data.
Hawthorne effect---changes that occur in people’s behavior because they know they are being studied.
Histogram---a graphic display of data frequency using rectangular bars with heights equal to the frequency count.
Hypothesis---a statement of the relationship between 2 or more study variables.
Independent variable---the conditions or factors that are explored in relationship to their influence on the dependent variable.
Indirect (inverse) relationship---a negative correlation between 2 variables.
Internal consistency reliability---the degree to which all items in a scale are measuring the same dimension of a concept.
Internal validity---a measure of the independent variable being responsible for an observed effect.
Inter-rater reliability---the reliability of measures across different raters.
Interval scale---measures data that rank orders a variable with equal distance between measurement points (eg, temperature data).
Instruments---devices or techniques used to collect data.
Likert scale---a scale of measurement in which respondents are asked to respond to statements based on how much they agree or disagree.
Literature review---the process of searching published work to find out what is known about a research topic.
Longitudinal study---a research study that is conducted over time and measures the same variables.
Mean---the average value or measure of central tendency. The mean is obtained by dividing the sum of values by the total number of values.
Median---the middle score.
Mode---the value that occurs most frequently.
Multiple regression---a statistical procedure for understanding the effects of 2 or more independent variables on a dependent variable.
N---used to designate the total sample size.
n---used to designate the number of subjects in a subgroup.
Nominal scale---a scale that measures data by assignment of characteristics into categories (eg, male=1, female=2).
Nonparametric statistics---tests that can be used to analyze nominal and ordinal data or data that are not normally distributed.
Null hypothesis---a statement that no relationship exists between study variables.
Ordinal scale---a scale that measures data that rank order values.
Parametric statistics---tests that are used to analyze interval level data and data that is normally distributed between 2 variables
Phenomenology---a qualitative research method that focuses on the lived experience of subjects.
Pilot study---a small scale study conducted to test the plan and method of a research study.
Power analysis---refers to a way of calculating the number of subjects needed for results of a study to be considered statistically significant.
Quasi-experimental---a type research design in which subjects are not randomly assigned to treatment conditions, but manipulation of the independent variable does occur.
R---the symbol that indicates the squared multiple correlation coefficient which indicates the amount of variance in the dependent variable accounted for or explained by the independent variable.
Random sample---a sample selected in a way that ensures that every subject has an equal chance of being included.
Range---represents the dispersion of data or the difference between the smallest and largest values.
Ratio scale---a scale that has a zero point and equal distances between scores.
Regression---a statistical procedure for predicting values of a dependent variable based on the values of one or more independent variables.
Reliability---refers to the consistency of the measures and means that an instrument produces consistent results or data with repeated use.
Research utilization---implemented of research findings in practice.
Respond rate---the rate of participation in a study
Scatter diagram (scatter plot) ---a graphic presentation of the correlation between two variables.
Significance level---the probability that an observed relationship could be caused by chance. A significance level of 0.5 indicates the probability that a relationship would be found by chance only 5 times out of 100.
Standard deviation---a measure of variability of data. The standard deviation is the average of the deviations from the mean.
Standard score (z-score) ---refers to how many standard deviations away from the mean a particular score is located.
Test-retest reliability---a method for determining the reliability of an instrument by administering it in 2 or more occasions to the same respondents.
Triangulation---refers to the use of several methods to collect data on the same concept.
T-test---a statistical test used to determine if the means of 2 groups are significantly different.
Type I error (alpha error)--- occurs when it is concluded that a difference between is not due to chance when in fact it is (reject a true null hypothesis).
Type II error (beta error)--- occurs when it is concluded that differences between groups were due to chance when in fact they were due to the effects of the independent variable (accepts a false null hypothesis.
Variable---a characteristic, attribute, or outcome.
Variability---the degree to which values are widely different or dispersed.
Validity---refers to the ability of the instrument to measure what it proposes to measure.
Variance---a descriptive statistic that examines how scores are distributed.
Z-score---a standard score, express in terms of standard deviations from the mean.
(taken from any sources)
