a variable that researchers hypothesize occurred after, and as a result of, another variable (called the independent variable)

e.g. height depends, in part, on gender

absolute/raw distribution

accuracy

ANOVA

ANOVA column

ANOVA cell

ANOVA row

APA style

assignable/attributable error

assumption

asymptotic

attenuation

attribute

average

axis

balanced design

bar chart

beta

between groups SS

bias

biased estimate

bimodal

A distribution that has two values that have the highest frequency of scores

binomial distribution

bivariate

case

In qualitative research, a particular instance of a phenomenon that is selected for study

causal-comparative

a type of quantitative investigation that seeks to discovery possible causes and effects of a personal characteristic or behavior pattern by comparing individuals in whom it is  present with individuals in whoem it is absent or present to a lesser degree

causation

central tendency

the score that reflects the most representative or typical score in a distribution

characteristic

Chi square

a nonparametric test of statistical significance that is used when the research data are in the form of frequency counts for two or more categories

class interval

coefficient of determination

compute a variable

confidence interval

construct validity

the extent to which a test can be shown to measure a particular psychological characteristic

content validity

the extent to which the items in a test represent the domain of content that the test is designed to measure

continuous data

correlation

correlation test

covariance

criterion validity

critical region

critical value

cross tabulation

cumulative distribution

cumulative relative distribution

curve

curvilinear

datum

decile

delimitation

dependent groups

descriptive statistics

mathematical techniques for organizing, summarizing, and displaying a set of numerical data

Statistics used to describe the characteristics of a distribution of scores

deviation score

df

dichotomous data

directional test

discrete data

dispersion

effect size

an estimate of the magnitude of a difference or relationship in the population represented by a sample

empirical

error

estimate

evaluation

experiment

a type of quantitative investigation that involves the manipulation of a treatment that is presumed to affect the dependent variable, to whose performance the control group's performance is compared

experimental/research design/methodology

A type of research in which the experimenter, or researcher, manipulates certain aspects of the research.  These usually include manipulations of the independent variable and assignment of cases to groups.

experimenter bias

external validity

the extent to which the results of a research study can be generalized to individuals and situations beyond those involved in the study

f distribution

F-test

F-ratio

fact

factor

a mathematical expression of a feature shared by a particular subset of quantitative variables that have been correlated

family/experiment-wise error rate

finite

frequency distribution

frequency

the total number of individuals in a sample who fit a particular category

Gaussian distribution

generalizability

The ability to use the results of data collected from a sample to reach conclusions about the characteristics of the population, or any other cases not included in the sample

grouped data

halo effect

harmonic mean

Hawthorn effect

histogram

homogenaity of variance

homoscedasticity

horn effect

hypergeometric distribution

hypothesis

the researchers' prediction, derived from a theory or from speculation, about how two or more measured variables, will be related to each other

independent variable

a variable that researchers hypothesize occurred before, and had an influence on, another variable (called the dependent variable)

Independent variables are often, but not always, manipulated by the researcher

independent groups

independent t-test

inferential statistics

a set of statistics that enable researchers to make inferences about a population based upon the descriptive statistics that are calculated from data for a sample drawn from the population

instrument

internal consistency reliability

internal consistency reliability

interval data

interval estimation

item analysis

item discrimination

kurtosis

layer

leptokurtic

level

limitation

line graph/chart

linear

main effect

Mann-Whitney

a nonparametric test of statistical significance that is used to determine whether the observed difference between the distribution of scores for each of two groups on a measured variable is statistically significant

margin of error

mean

a measure of central tendency corresponding to the average of a set of scores

the arithmatic average of a distribution of scores

mean square

measure

measurement

median

a measure of central tendency corresponding to the average of a set of scores

the score in a distribution that marks the 50th percentile.  It is the score at which 50% of the distribution falls below and 50% falls above.

metrology

midpoint

missing value

mode

a measure of central tendency corresponding to the most frequently occurring score in a distribution of scores

model

mu

μ

n and N

negative skew

In a skewed distribution, when most of the scores are clustered at the higher end of the distribution with a few scores creating a tail at the lower end of the distribution

nominal/categorical data

A variable in which the numerical values assigned to each category are simply labels rather than meaningful numbers

non directional test

non parametric

mathematical techniques for analyzing scores that do not involve assumptions about their distribution or form

normal error

normal curve

a distribution of scores that forms a symmetrical, bell-shaped curve when plotted on a graph

normal score

null hypothesis

the prediction that an observed result for a sample is a chance finding

obtained score/value

one-sample t-test

one-tailed test

one-way ANOVA

ordinal data/variable

Variables measured with numerical values where the numbers are meaningful (e.g., 2 is larger than 1) but the distance between the numbers is not constant

p value

p-test

pair-wise error rate

paired t-test

parameter

a statistic that applies to the entire population rather than just to a sample

parametric

mathematical techniques for analyzing scores that involve particular assumptions about their distribution and form

Pareto diagram

Pearson production moment

 precentile score

a type of rank score that represents a given raw score on a measure as the percentage of individuals in the sample or norming group whose score falls at or below that score

percentile rank

percentile

philosophy

pie chart

platykurtic

point estimation

Poisson distribution

population

The group from which data are collected or a sample is selected.  The population encompasses the entire group for which the data are alleged to apply

population mean

positive skew

In a skewed distribution, when most of the scores are clustered at the lower end of the distribution with a few scores creating a tail at the higher end of the distribution

power

skew

a distortion in what is actually a central point in the set or distribution of scores

When a distribution of scores has a high number of scores clustered at one end of the distribution with relatively few scores spread out toward the other end of the distribution, forming a tail.

an instrument that measures personal characteristics by totaling the individual's responses to items having a fixed number of response options

sampling distribution

sample mean

sample

An individual or group, selected from a population, from whom or which data are collected

sample size

rho

review of literature

research

research substantive question

(research) problem

repeatability

reliability

a measure of the extent to which a test or other measure is free of measurement error

relative distribution

reject region

regression toward the mean

regression constant

regression weight

regress

recode a variable

raw score

ratio data

range

The difference between the largest score and the smallest score of a distribution

randomization

random

random sampling

Selecting cases from a population in a manner that ensures each member of the population has an equal change of being selected into the sample

random error

quartile

quantitative

inquiry that is grounded in the assumption that features of the social environment constitute an objective reality that is relatively constant across time and settings; the dominant methodology for studying these features is to collect numerical data on the observable behavior of samples and subject them to statistical analysis

qualitative variable

A variable that has discrete categories.  If the categories are given numerical values, the values have meaning as nominal references but not as given numerical values

e.g., in 1 = "male" and 2 = "female", 1 is not more or less than 2

standard deviation

The average deviation between the individual scores in the distribution and the mean for the distribution

statistic

A value derived from the data collected from a sample

a characteristic, or value, derived from sample data

sums of squares

of

sum of squared deviations

The sum of each squared deviation for all of the cases in the sample

variance

The sum of the squared deviations divided by the number of cases in the population, or by the number of cases minus one in the sample

distribution

A collection, or group, of scores from a sample on a single variable.  Often, but not necessarily, these scores are arranged in order from smallest to largest.

Median split

Dividing a distribution of scores into two equal groups by using the median score as the divider.  

Scores above the median are the "high" group whereas those below the median are the "low" group.

multimodal

When a distribution of scores has two or more values that have the highest frequency of scores

Outliers

Extreme scores that are more than two standard deviations above or below the mean

Σ 

The sum of; to sum

X

An individual score in a distribution

ΣX

The sum of an individual score in a distribution (X); additing up all of the scores in a distribution

_

X

The mean of a sample(shown as X bar)

Sometimes shown as M

μ 

The mean of a population

n

The number of cases, or scores, in a sample

N

The number of cases, or scores, in a population

P₅₀

Symbol for the median

Constant

A construct that has only one value (e.g. if every member of a sample was 10 years old, the "age" construct would be a constant)

Convenience sampling

Selecting a sample based upon ease of access or availability

Correlational research design

A style of research used to examine the associations among variables.

Variables are not manipulated by the researcher in this type of research design

Dichotomous variable

A variable that has only two discrete values (e.g., a pregnancy variable can have a value of 0 for "not pregnant" and 1 for "pregnant"

Interval variable

or

Ratio variable 

Variables measured with numerical values with equal distance, or space, between each number

e.g., 2 is twice as much as 1, 4 is twice as much as 2, the distance between 1 and 2 is the same as the distance between 2 and 3

qualitative research

quantitative (continuous) variable

A variable that has assigned values and the values are ordered and meaningful, such that 1 is less than 2, 2 is less than 3, and so on.

random assignment

Assignment of members of a sample to different groups randomly, or without consideration of any of the characteristics of sample members

e.g. experimental and control

representative sampling

a method of selecting a sample in which members are purposely selected to create a sample that represents the population on some characteristic(s) of interest

e.g. when a sample is selected to have the same percentages of various ethnic groups as the larger population

sample

A collection of cases selected from a larger population

variable

Any construct with more than one value that is examined in research

boxplot

A graphic representation of the distribution of scores on a variable that inclues the range, the median, and the interquartile range

Interquartile range (IQR)

The difference between the 75th percentile and the 25th percentile scores in a distribution

squared deviation

The difference between an individual score in a distribution and the mean for the distribution, squared

s²

The sample variance

s

The sample standard deviation

σ 

The population standard deviation

σ²

The population variance

SS

The sum of squares, or sum of squared deviations

Mutually exclusive categories

when values can fit into only one class or category