Unit 3 Stats Vocab

Population

Population

Entire group of individuals about which we want information from

Sample

Part of the population from which we actual collect information

Simple Random Sample

Consists for n individuals from the population chosen in such a way that every set of n individuals has an equal chance to be the sample actually selected

Convenience Sample

Choosing individuals that are easiest to reach

Voluntary sample

Consists of people who choose themselves by responding to a general appeal

Stratified Random Sample

Grouping a sample into groups, randomly generating n individuals from each group, such that each group has an equal chance of being selected.

Cluster Random Sample

Grouping a sample into groups, randomly generating a group and choosing all the individuals from that group.

Systematic random sample

Where every nth individual is chosen to be included.

Sample survey

Study that collects data from a sample that is chosen to represent a specific population

Observational study

Observe individuals and measure variables of interest but do not attempt to influence responses.

Experiment

Imposes some treatment on individuals to measure responses

Explanatory variable

variable believed to explain or influence changes in another variable (independent variable)

Response variables

variables being measured to see how it changes in response to variations in the explanatory variable.

Confounding variable

2 variables that are associated with that their effects on the response variable can be distinguished

Prospective study

individuals are selected and tracked into the future

Retrospective study

uses existing data for a sample of individuals

treatment

specific condition applied to individuals

experimental units

individuals to which treatments are applied to

subjects

human individuals

factor

explanatory variable

level

value of factor

completely randomized design

where a sample is randomly assigned into explanatory variable groups and then compared

randomized block design

where a sample is split into groups, and each group is randomly assigned into explanatory variable groups. Explanatory variable groups and the sample groups are compared.

matched pair design

format sample individuals into a list based on the confounding variable, pair the highest individuals with the lowest individuals. Randomly assign pairs into explanatory groups. Compare results.

placebo

fake treatment

placebo effect

when a subject believes they had an effect even though they had a fake treatment

single blind

when subjects do not know if they were given the placebo or treatment

double blind

when subjects and experimenters don’t know who was given the placebo or treatement

statistically significant

when the difference of means is above the expected difference in means by 5%.