Chapter2

# Chapter2 - Topic of this chapter Looking at Data...

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1 Looking at Data – Relationships Topic of this chapter • Relationships between two variables • The two variables are measured on the same individuals (or subjects), e.g. weight & height, GPA & mother’s education level. • Covered by about 2 lectures • Skip: linear regression Introduction: associations between two variables When there is a causal relationship: Response variable : measures an outcome of a study. Explanatory variable : explains or causes changes in the response variables. However • There may not be distinction of response vs. explanatory between two variables, e.g. city and highway gas mileages for two-seater cars. • Many explanatory-response relationships do not involve direct causation, e.g. high school SAT scores and college grades. Examples 1 & 2 How does drinking beer affect the level of alcohol in blood ? Response variable : the level of alcohol in blood after 30 minutes. Explanatory variable : cans of beer consumed.

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## This note was uploaded on 09/01/2011 for the course ECON 2500 taught by Professor Xianghongli during the Fall '11 term at York University.

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Chapter2 - Topic of this chapter Looking at Data...

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