Stats Unit 1

Frequency

a simple count, like counting on your fingers

Position

rank; where something is/how it compares to others

Central Tendency

mean (average), median, and mode

Variation

range, interquartile range, variance, standard deviation

Inferential Statistics

using a sample to make inferences about an entire population

Nominal Data

labels that can’t be given any value (hair color, eye color)

Ordinal Data

categories that have an inherent sequence, but are not numerical (birth month, days of the week)

Discrete Data

numerical values that are separate and can be listed, usually a count of something (age in years, number of siblings)

Continuous Data

numerical values within a range, can be fractions or decimals

Uniform Histogram

mostly the same height

Symmetric Histogram

mirror image

Skewed Right

heavy on the left, tail on the right

Skewed Left

Heavy on the right, tail on the left

Unimodal

1 bump

Bimodal

2 bumps

Multimodal

many bumps

Simple Random Sampling

random (random number generator)

Stratified Random Sampling

Divide the population into groups, then take a random number from each group that is proportional to the group size

Systematic Random Sampling

Divide population by sample size (m), use a random number generator to pick between 1 and m for your starting location (k), then pick by m (ex: k, k+m, k+2m, k+3m…)

Cluster Sampling

divide the population into groups, use a rng to pick random groups, choose all samples in each group

x bar

sample mean

𝜇

mu; population mean

σ

sigma; population standard deviation

s

sample standard deviation

Interquartile Range Equation

Q3 - Q1

What does the IQR describe

the middle 50% of the data; it is resistant to outliers

Q1

median between min and true median

Q2

true median

Q3

median between true median and max

Lower Outlier Formula

Q1-(IQR x 1.5)

Upper Outlier Formula

(IQR x 1.5)+Q3

What is the difference between the outlier formulas and the extreme outlier formulas?

extreme outlier formulas multiply by 3

Parts of the Five-Number Summary

Min, Q1, Median (Q2), Q3, Max