AP Stat Test 2

Blocking

Grouping already selected subjects into subgroups (blocks) and then randomly assigning each block to treatments.

Purpose of blocking

To reduce variability so that differences can be more easily seen.

Direct control

A method to reduce variability for clearer observation of differences.

Completely randomized experiment design

The most common type of experiment where subjects are randomly assigned to treatments.

Matched pairs experiment

An experimental design where either both treatments are given to a single individual or subjects are matched based on similar characteristics before randomizing treatments.

Point of matched pairs experiments

To reduce within-subject variability.

Control group

A group that receives no treatment, used for comparison against a treatment group.

Placebo

A treatment that appears identical to another but contains no active ingredients, serving as a secret control group.

Single blind

An experimental design where subjects do not know which treatment they are receiving, but the measurers do.

Double blind

An experimental design where neither the subjects nor the measurers know which treatment is being administered, although the experimenter does.

Dot plot

A chart used for displaying numerical data.

Bar chart

A chart used for displaying categorical data.

Mosaic chart

In this chart, each bar's width represents its frequency.

Random selection using random numbers

Choose two numbers at a time, where 01-30 represent people, ignoring 31-99 and repeats until three people are selected.

Number of classes for a histogram

Calculated as the square root of the number of observations.

Class width/intervals

Determined by the formula class width = (high - low) / number of classes.

Left skewed

Another term for negatively skewed data.

Right skewed

Another term for positively skewed data.

Fixing unequal intervals

Achieved by dividing the frequency by the width, known as density.

Bad graphing practices

Poor scaling, such as not starting at zero, can exaggerate differences in graphs.

Scatter plots

Used for displaying bivariate data (numerical data).