Research Designs

research design

specific method a researcher uses to collect, analyze, and interpret data

descriptive research

research designed to provide a snapshot of the current state of affairs

correlational research

research designed to assess the relationships between and among two or more variables

experimental research

research designed to assess the causal impact of one or more experimental manipulations on a dependent variable

case studies

descriptive records of one or more individuals' experiences and behavior

survey

a measure administered through either a face-to-face or telephone interview, or a written or computer-generated questionnaire, to get a picture of the beliefs or behaviors of a sample of people of interest

sample

people chosen to participate in research

population

all of the people that the researcher wishes to know about

naturalistic observation

research based on the observation of everyday events occurring in the natural environment of people or animals

observer bias

the individual observing behavior is influenced by their own experiences, expectations, or knowledge about the purpose of the observation or study

observer effect

interference with or modification of the subject's behaviors by the process of observation

interrater reliability

estimate of how much agreement there is between the two observers about what the subjects were doing

independent variable

causing variable that is created (manipulated) by the experimenter

dependent variable

measured variable that is expected to be influenced by the experimental manipulation

random assignment to conditions

procedure in which the condition that each participant is assigned to is determined through a random process, such as drawing numbers out of an envelope or using a random number table

quasi-experimental design

compares two groups that already exist in the population

scatter plot

visual image of the relationship between two variables

linear relationship

when the association between the variables on the scatter plot can be easily approximated with a straight line

Pearson correlational coefficient (r)

most common statistical measure of the strength of linear relationships

common-causal variable

variable that is not part of the research hypothesis but that causes both the predictor and the outcome variable and thus produces the observed correlation between them

spurious relationship

relationship between two variables in which a common-causal variable produces and "explains away" the relationship

threats to internal validity

although it's claimed that the independent variable caused the dependent variable, the dependent variable actually may have been caused by a confounding variable

threats to external validity

although it is claimed that the results are more general, the observed effects may actually only be found under limited conditions or for specific groups of people

internal validity

extent to which we can trust the conclusions that have been drawn about the causal relationship between the independent and dependent variables

confounding variables

variables other than the independent variable on which the participants in one experimental condition differ systematically from those in other conditions

experimenter bias

a situation in which the experimenter subtly treats the research participants in the various experimental conditions differently, resulting in an invalid confirmation of the research hypothesis

double-blind experiment

both the researcher and the research participants are blind to condition

external validity

extent to which the results of a research design can be generalized beyond the specific way the original experiment was conducted

generalization

extent to which relationships among conceptual variables can be demonstrated in a wide variety of people and a wide variety of manipulated or measured variables

replication

process of repeating previous research, which forms the basis of all scientific inquiry