PsychStats

Statistics

the backbone of psychological research

Psychology

it is the scientific study of the mind and behavior.

Goals of Psychology

Descrive, Understand or Explain, Predict, and Control

Statistics

Organize, Summarize, Analyze, and Interpret

Population

entire group of individuals

Target Population

ideal group

Accessible Population

portion

Study Population

actual group selected

Parameter

numerical value fhat describes a population

Population Mean

average score

Population Standard Deviation

how spread out those scores are

Population Proportion

percentage oof people

Sample

subset of individuals

Representative Sample

accurately reflects the characteristics

Random Sampling

equal chance of being selected

Sample Size

number of individuals

Population and Sample

foundational; study a part to understand the whole

Variable

building blocks of research; measurable

Independent Variable (IV)

manipulated by the researchers to observe its effects

Dependent Variable (DV)

the outcome is measured to see if it changes due to the IV

Extraneous Variable

uncontrolled; might influence the DV

Confounding Variable

linked to both IV and DV, potentially distorting results

Controlled Variable

kept constant to prevent them from affecting DV

Intervening Variable

mediates IV and DV

Value

specific numbers that a variable can take on

Numerical Value

represents measurable quantities

Categorical Value

classifies data

Ordinal Value

meaningful order, but not equal interval

Binary Value

only two possible outcomes

Score

numerical value that represents a person’s performance

Raw score

unadjusted number

Standard Score

allows comparison

z-score

how far a score is from the mean

T-score

mean of 50, SD of 10

Percentile Score

percentage of scores

Scaled score

fixed ranges

Data/Datus

collected information

Quantitative

measurable and numeric

Qualitative

descriptive and categorical

Cross-sectional

one point in time

Longitudinal

over a period of time

Experimental

controlled studies

Observational

natural settings

Data Set

structured collection of information

Descriptive Statistics

simplifies data

Inferential Statistics

goes beyond the data

Sampling Error

natural difference between characteristics

Discrete Variable

countable

Continuous Variable

measurable

Dichotomous Variable

only two possible categories

Artificial Dichotomous

scores

True Dichotomous

naturally occuring

Nominal Scale

no quantitative value

Ordinal Scale

natural order, no quantifiable difference

Interval Scale

no “true zero”

Ratio Scale

has “true zero”