# AP Statistics Vocab Set 2

### 27 terms by Gie23

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math vocab helping to prepare for the AP Stats test

### Median

Middle value. Usually used when data is skewed

High-Low

### 1st Quartile

25% of data lies below

### 3rd Quartile

75% of data lies below

Q3-Q1

### 5 Number Summary

Same as a box and whisker plot (min, max, Q1, Q3, Median)

### Mean

A measure of center used when data are symmetric

### Standard Deviation

Measure of Spread - tells the average distance each value is away from the mean

### Time Plot

Displays data that change over time

### Parameter

A population measure

### Statistics

A sample measure that is calculated from a set of data

### Z-Score

Tells how many standard deviations a value is away from the means. They do not have units, so we can compare two different values.

### 65-95-99.7 Rule

Says 68% fall within 1 standard deviation, 95% of data fall within 2 standard deviations, 99.7% of data fall within 3 standard deviations

### Response Variable

Variables that you hope to predict or explain (Y)

### Explanatory Variable

Variables that you can use to account for, explain or predict the Y variable (X)

### Correlation Coefficient

A number that measures direction and strength of a linear association

### Lurking Variable

A variable other than X and Y that affects both variables accounting for the correlation between the two

### Residual

Differences between data values and corresponding predicted values

### Slope

b₁ gives a value in Y units per X

### Intercept

b₀ is the value of Y when X is zero

### Sё

Standard deviation of residuals

### R²

Overall measure of how successful the regression is in linearly relating Y to X

### Extrapolation

When we use regression to predict the future

### Leverage

Data points that pull the line lose to them so they can have a great effect on slope and intercept

### Influential point

A point that when omitted will give very different results

Places an order to re-expression we must do

### Scatterplots

Shows relationship between two quantitative variables

Example: