Research Methods

Theories

Organized sets of concepts that explain phenomena.

Hypothesis

Prediction of how two or more factors are likely related.

Replication

Repetition of the methods used in a previous experiment to see whether the same methods will yield the same results.

Operational Definition

A description of the specific procedure used to determine the presence of a variable.

Independent Variable (IV)

The factor the researcher manipulates in a controlled experiment (the cause).

Dependent Variable (DV)

The behavior or mental process that is measured in an experiment or quasi-experiment (the effect).

Confounding Variables

Factors other than the independent variable that may cause a result.

Population

All of the individuals in the group to which the study applies.

Sample

The subgroup of the population that participates in the study.

Random Assignment

The process of assigning participants to different conditions in an experiment randomly.

Random Selection

The process of selecting participants from a population randomly, primarily used in correlational studies and surveys.

Cause and Effect

Experiments are useful for determining cause and effect.

Experimental Controls

The use of experimental controls reduces alternative explanations.

Correlational Research

Can indicate if there is a relationship or association between two variables but cannot demonstrate cause and effect.

Representativeness

The goal in selecting a sample is that it will be representative of a large population.

Doing Well in School

Operational definitions for 'doing well' could include class rank, GPA, attendance, and assignment completion percentages.

Experimental Group

a subgroup of the sample that receives the treatment or independent variable

Control Group

the comparison group; the subgroup of the sample that is similar to the experimental group in every way except for the presence of the independent variable

Single-Blind Procedure

research design in which participants don't know whether they are in the experimental or control group

Double-Blind Procedure

research design in which neither the experimenter nor the participants know who is in the experimental group and who is in the control group

Placebo

a physical or psychological treatment given to the control group that resembles the treatment given to the experimental group, but that contains no active ingredient

Placebo Effect

a response to the belief that the independent variable will have an effect, rather than the actual effect of the independent variable, which can be a confounding variable

Reliability

consistency or repeatability of results

Validity

the extent to which an instrument measures or predicts what it is supposed to measure or predict

Experimenter Bias

a phenomenon that occurs when a researcher's expectations or preferences about the outcome of a study influence the results obtained

Hindsight Bias

the tendency upon hearing about research finding (and many other things) to thinking that one knew it all along

Demand Characteristics

clues participants discover about the purpose of the study that suggest how they should respond

Statistics

a field that involves the analysis of numerical data about representative samples of populations

Descriptive Statistics

numbers that summarize a set of research data obtained from a sample

Frequency Distribution

an orderly arrangement of scores indicating the frequency of each score or group of scores

Measures of Central Tendency

average or most typical scores of a set of research data or distributions (mode, median, mean)

Mode

most frequently occurring score in a set of research data

Median

the middle score when a set of data is organized by size

Mean

the arithmetic average of a set of scores

Measures of Variability

the spread or dispersion of a set of research data or distribution

Range

the difference between the largest score and the smallest score

Standard Deviation (SD)

measures the average difference between each score and the mean of the data set

Normal Distribution

bell-shaped curve that represents data about how lots of human characteristics are dispersed in the population

Percentile Score

the percentage of scores at or below a particular score (from 1 to 99)

Correlation Coefficient (r)

a statistical measure of the degree of relatedness or association between two sets of data that ranges from -1 to +1

Inferential Statistics

statistics that are used to interpret data and draw conclusions

Statistical Significance (p)

how likely it is that an obtained result occurred by chance

Informed Consent

signed agreements from all participants that describe procedures, risks, benefits, and the right to withdraw from the study without penalty

Institutional Review Boards (IRBs)

public and private institutions that must approve all research conducted within their institutions

Debriefing

the process of revealing the nature, results, and conclusions of the research to participants after their involvement

Animal Research (IACUC)

must treat animals humanely and minimize their discomfort, infection, illness, and pain

Ethical Guidelines

suggested rules for acting responsibly and morally when conducting research or in clinical practice

Harry Harlow's Studies

involved rhesus monkeys separated from their mothers and subjected to frightening conditions

Phil Zimbardo's Studies

involved students role-playing prisoners and guards

Stanley Milgram's Studies

involved participants believing they were delivering painful electric shocks to another person

p-value

must be ≤ .05 for statistical significance to exist

Statistical Significance Criteria

results are likely to be statistically significant when there is a large difference between the means of the two frequency distributions, when their standard deviations are small, and when the samples are large