# STAT 100 Study Guide - Midterm Guide: Quartile, Sample Space, Confounding

17 pages141 viewsFall 2018

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STAT 100

Chance and Data Analysis

Winter 2018

Term Test 2

Professor: Gamage Perera

Exam Guide

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Table of content:

- Chapter 13: Normal Distributions

- Chapter 14: Describing Relationships: Scatterplots and Correlation

- Chapter 15: Describing Relationships: Regression, Prediction, and Causation

- Chapter 18: Probability Models

-Chapter 19 and 20: Expected value and Simulation

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Chapter 13: Normal Distributions

Density$curves$

•Exploring!a!distribution

oAlways!plot!your!data

§Make!a!stemplot!or!histogram

oLook!for!the!overall!pattern

oCalculate!a!numerical!summary!to!briefly!describe!center!and!variability

oSometimes!the!overall!pattern!of!a!large!number!of!observations!is!very

regular!that!we!can!describe!it!by!a!smooth!curve

§Usually!putting!a!smooth!curve!over!a!histogram

•A!density!curve!is!a!curve!that:

oIs!always!on!or!above!the!horizontal!axis

oHas!an!area!of!exactly!1!underneath!it

•A!density!curve!describes!the!overall!pattern!of!a!distribution.!The!area!under

the!curve!and!above!any!range!of!values!on!the!horizontal!axis!is!the!proportion

of!all!observations!that!fall!in!that!range

Describing$density$curves$

•The!median!of!a!density!curve!is!the!equal-areas!point,!the!point!that!divides!the

area!under!the!curve!in!half

•The!mean!of!a!density!curve!is!the!balance!point!at!which!the!curve!would

balance!if!made!of!solid!material

•The!median!and!mean!are!the!same!for!a!symmetric!density!curve

•The!mean!of!a!skewed!curve!is!pulled!away!from!the!median!in!the!direction!of

the!long!tail

•The!mean!and!standard!deviation!computed!by!“x!bar”!and!“s”!respectively

•The!mean!and!standard!deviation!of!the!actual!distribution!represented!by!the

density!curve!denoted!by!“μ”!(mu)!and!“σ”!(sigma)!respectively

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