Stats Exam 1 Definitions

Population

A collection of persons, things or objects

Parameter

Numerical characteristics of a population (Greek letters)

Sample

A subset of a population

Statistic

An estimate of a population parameter, generated from a sample (Roman letters)

Variable

A characteristic that can be determined for every population member

Quantitative Data

Data that are numbers; values that can be counted

Categorical data

Data that fit into define, non-numeric categories

Simple random Sampling

Randomly select from a list of the population

Stratified random Sampling

Seperate the population by certain “stratum” and randomly sample them

Cluster random Sampling

Randomly sample defined clusters and include all members of the cluster

Systematic Sampling

Select every n-th member of the population

Convenience Sampling

Take units that are readily available

Ordinal measurement

Categorical data that can be ordered and doesn;t make sense to do math on

Nominal measurement

Categorical data w/ no natural ranking/order

Interval measurement

Quantitative data we can add/subtract w/o a natural “zero” point

Ratio measurement

Quantitative data with a natural zero point

Univariate statistics

One-variable statistics, talking about 1 single variable

Bivariate statistics

How multiple variables are distributed in statistics

Percentile

What % of a population has that value or less?

Mode

What # occurs most frequently in the data set?

Mean

Sum of all the values divided by the number of values

Variance

Shows the spread of data

Standard Deviation

The square root of the variance

Experiment

Controlled conditions to observe a pre-defined outcome

Outcome

Result of an experiment

Sample space

All the possible outcomes of the experiment

Event

Defined combination of one or more outcomes

Probability

Long-run frequency of an event over repeated experiments

Random variable

Outcome of a statistical experiment

Fixed variable

Set or fixed by the experiment

Probability distribution function

Math function that describes the probability of each possible outcome of a random variable