Statistics Teminology

statistics

the study of procedures for collecting, describing, and drawing conclusions from information

population

the complete collection of objects or individuals that are being studied

sample

a subset of the population

data

the information we collect

parameters

data values that are reflective of the entire population

statistic

a calculation using the data from the sample

descriptive statistics

involves the collection, presentation, and description of the data

inferential statistics

refers to the processes used to take information from the descriptive statistics and interpret that information in a way that allows us to draw conclusions or make decisions

variables

the things of interest that we wish to learn from our sample or the population

qualitative variables (aka categorical variables)

involves categories

ordinal variables

categories that have natural order (ex. A, B, C, …)

nominal variables

report categories that do not have natural order (ex. gender, race, eye color, …)

identifier

a categorical variable with exactly one observation in each category (ex. SSN, KSU ID, …)

quantitative variables

can be measured numerically

discrete variables

quantitative values that can be listed (not decimals)

continuous variables

quantitative variables that have an uncountable number of possible values (decimals)

sampling

process of selecting the sample

simple random sample (SRS)

a sample selected by the method where each combination of experimental units has an equal chance of being selected

convenience sample

a sample is selected by taking the members of the population that are easiest the reach

stratified random sample

a sampling design in which the population is divided into several subpopulations (called strata) and simple random samples are drawn from each stratum

cluster sampling

a sampling design in which entire groups, or clusters, are chosen at random

systematic sampling

a sampling process in which the method for choosing subjects is very systematic