handout_2_6

handout_2_6 - 2.6 The Question of Causation Often the goal...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
2.6 The Question of Causation Often the goal in a study is to establish that changes in the explanatory variable cause changes in the response variable. What constitutes good evidence of causation? What different types of links between x and y can explain an observed association between x and y ? dotted line→ association between x and y unbroken line→ cause-and-effect link between x and y Causation - “ x causes y Example #1 x = mother’s body mass index y = daughter’s body mass index
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Common Response The observed association between the variables x and y is explained by a lurking variable z . Both x and y change in response to changes in z . This common response creates an association even though there may be no direct causal link between x and y . Example #1 x = the student’s SAT score y = the student’s first-year college GPA z = ability Example #2 x = private health spending in a given year ($ billions) y = goods imported in a given year ($ billions) z = general economic conditions in a given year 2
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/23/2011 for the course STAT 2700 taught by Professor Bill during the Spring '11 term at Adelphi.

Page1 / 4

handout_2_6 - 2.6 The Question of Causation Often the goal...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online