General vocab/definitions

Confidence interval

point estimate ± MoE

Margin of error

t\*(SE)

Standard error

likelihood of difference between population and sample mean σ/sqrt(n)

Null hypothesis

Ho

Alternative hypothesis

Ha

p-value

Probability of sample mean given that Ho is true

Chi Squared (χ²)

Test stat for many proportions

Alpha level (α)

Boundary used to decide test

Type 1 error

Rejecting Ho when true

Type 2 error

Failing to reject Ho when false

Skew

State of asymmetry

Statistic

Value calculated from data used to summarize the sample

Parameter

Any value used to represent the population

Measures of center

Mean and median

Categorical variable

Data graphed with a pi chart or segmented graph

Quantitative variables

Data graphed with a boxplot, histogram, or stem plot

Z-score

Measurement that shows a values distance from the mean in standard deviations (x - μ) / σ

Percentile

The value below which a certain percent of the distribution will lie

Outlier

Extreme values that don’t belong with the rest of the data

Measures of spread

Standard deviation, range, IQR

Inference

Using sample data to estimate/test population parameters

1\.5 IQR test

Q1-((Q3-Q1)1.5) & Q3+((Q3-Q1)1.5)

Model

An equation or formula that simplifies and represents reality

Residual

Differences between data values and the values predicted by the model

Regression line/Line of best fit

Linear representation of a scatterplot

R^2

The fraction/percent variability the regression line accounts for in our data

Extrapolation

Making predictions outside the x values of our data

Leverage

Data points that are far from the mean have more ________

Influential point

When omitted, these points change the slope of the data set