PSY 200 VOCAB

Vocabulary

Statistics

a set of mathematical procedures for organizing, summarizing, and interpreting information 

Population

the set of all the individuals of interest in a particular study. NOT just humans, whatever area is of focus 

Sample

a set of people selected from a population

Random Sample

everyone in the population has an equal chance of being selected 

Variable

characteristic or condition that changes or has different values for different individuals 

Data

measurement of operations 

Data Set

collection of measurements or observations

Datum

single measurement or observation **also called a raw score  

Parameter

value, usually numerical, describes a population 

Statistic

value, usually numerical, describes a sample 

Descriptive Statistics

statistical procedures used to summarize, organize, and simplify data 

Inferential Statistics

techniques that allow us to study samples and make generalizations about the populations from which they were selected 

Sampling Error

naturally occurring discrepancy that exists between a sample statistic and the corresponding population parameter 

Constructs

internal attributes or characteristics that cannot be directly observed but are useful for describing or explaining behavior 

Operational Definition

identifies a measurement procedure (set of operations) for measuring an external behavior, and uses the results as a definition and a measurement as a hypothetical construct 

Discrete Variable

consists of separate, invisible categories. No values can exist between two neighboring categories 

Continuous Variable

infinite number of possible values between any two observed values. A continuous variable is divisible into an infinite number of fractional parts 

Real Limits

the boundaries of intervals for scores that are represented on a continuous number line 

Upper & Lower Real Limit

top & bottom of interval, respectively

Nominal Scale

consists of categories with different names. Label and categorize, but do not make quantitative distinctions 

Ordinal Scale

a set of categories that are in an organized sequence. Rank observations by size or magnitude  

Interval Scale

ordered categories that are all intervals of (exactly) the same size 

Ratio Scale

interval scale with an absolute zero point 

Descriptive Research

measuring one or more separation variables for each individual, with the intent of simply describing the individual variables 

Correlation Method

two different variables are observed to determine if there is a correlation between them 

Experimental Method

one variable is manipulated which the other variable is observed and measured 

Individual Differences

differences between participants 

Independent Variable

manipulated variable 

Dependent Variable

observed variable 

Controlled Condition

no treatment (e.g. placebo group) 

Experimental Condition

variable is introduced (e.g. group with drug) 

Quasi-Independent Variable

non-experimental study that is used to create different groups of scores (independent variable) 

Frequency Distributions

an organized tabulation of the number of individuals located in each category on the scale of measurement 

Percentile Rank

the percentage of individuals with scores above or below the particular value 

Summation Symbol

∑

Central Tendency

a statistical measure to determine a single score that defines the center of a distribution

The Mean

the sum of the scores divided by the number of scores

Median

mid-point of scores

The Mode

score of category that has the greatest frequency

The Weighted Mean

combination of two scores

Variability

a quantitative measure of the differences between scores in a distribution and describes the degree to which scores are spread out/or clustered together  

Z-score

the precise location of each x value within a distribution