### Hindsight Bias

the tendency to believe, after learning an outcome, that one would have foreseen it. (Also known as the I-knew-it-all-along phenomenon)

### Hypothesis

a proposal intended to explain certain facts or observations (expresses a relationship between two variables)

### Dependent Variable

the outcome factor; the variable that may change in response to manipulations of the independent variable

### Independent Variable

the experimental factor that is manipulated; the variable whose effect is being studied

### Theory

aims to explain some phenomenon and allows researchers to generate testable hypotheses with the hope of collecting data that support the theory

### Operational Definitions

clear, precise definitions and instructions about how to observe and measure concepts and variables

### Population

the mass from which the sample will be selected from; includes anyone or anything that could possibly be selected to be in the sample

### Random Selection

every member of the population has an equal chance of being selected: increases the likelihood that the sample represents the population and that one can generalize the findings tot he larger population

### Stratified sampling

process that allows a researcher to ensure that the sample represents the population on some criteria (example proportion group sizes)

### Laboratory experiments

are conducted in a lab, a highly controlled environment (can control variables)

### Random Assignment

means that each participant has an equal chance of being placed into any group (limits the effect of participant relevant confounding variables)

### Participant-relevant confounding variables

the differences amongst participants; random assignment avoids this

### Experimenter bias

is the unconscious tendency for researchers to treat members of the experimental and control groups differently to increase the chance of confirming their hypothesis

### Double-blind procedure

occurs when neither the participants nor the researcher are able to affect the outcome of the research

### Single blind

occurs when only the participants do not know to which group they have been assigned (strategy minimizes the effect of demand characteristics, response, or participant bias)

### Response or subject bias

is the tendency for subjects to behave in certain ways (Example: social desirability)

### Hawthorne Effect

The effect that merely selecting a group of people on whom to experiment has been determine to affect the performance of that group

### Placebo Effect

Method of control that allows researchers to separate the physiological effects of the drug from the psychological effects of people thinking they took the drug. (some people will receive the drug, others will receive placebos)

### Counterbalancing

A procedure that uses participants as their own control group, Alternating the order in which participants perform in different conditions of an experiment. For example, group 1 does 'A' then 'B', group 2 does 'B' then 'A' this is to eliminate order effects.

### Order effects

changes in a subjects performance resulting from the position in which a condition appears in an experiment

### Ex post facto study

to seek to control all other aspects of the research process because the assignment of the independent variable has been predetermined

### Survey method

involves asking people to fill out surveys, can be used to investigate whether there is a relationship between the two variables

### Naturalistic observation

unobtrusive observation: goal is to get a realistic and rich picture of the participants' behavior

### Case study method

used to get a full, detailed picture of one participant or a small group of participants

### Frequency distribution

a distribution of observed frequencies of occurrence of the values of a variable

### mean

add up all the scores in the distribution and divid by the number of scores, the average (measure of central tendency)

### mode

the number that occurs the most often, distribution may have more than one mode (a distribution is bimodal)

### extreme scores (outliers)

the number that is out of place, often distorts the accuracy of the central tendency