Spurious relationship l.jpg
This presentation is the property of its rightful owner.
Sponsored Links
1 / 25

Spurious Relationship PowerPoint PPT Presentation


  • 294 Views
  • Uploaded on
  • Presentation posted in: General

Spurious Relationship. A correlation between two variables that have no causal relationship; both variables are caused by another variable. Example: Water causes drunkenness. . Once a group of students decided to study empirically the causes of drunkenness.

Download Presentation

Spurious Relationship

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Spurious relationship l.jpg

Spurious Relationship

A correlation between two variables that have no causal relationship; both variables are caused by another variable


Example water causes drunkenness l.jpg

Example: Water causes drunkenness.

  • Once a group of students decided to study empirically the causes of drunkenness.

    • They drank vodka and water. Got drunk.

    • They drank rum and water. Got drunk.

    • They drank scotch and water. Got drunk.

    • They drank bourbon and water. Got drunk.

    • They drank gin and water. Got drunk.

  • Conclusion: Water causes drunkenness


Examples of spurious relationships l.jpg

Examples of spurious relationships

  • Amount of ice cream sold and death by drowning (units are months)

  • Number of doctors and number of people dying of disease (by city)

  • Number of churches and number of homicides (by city)

  • Number of libraries and number of people on drugs (over time)


What causes the price of rum l.jpg

What causes the price of rum?

  • There is a positive relationship between the salaries of Presbyterian ministers in Massachusetts and the price of rum in Havana.

  • What is the causal mechanism?


Causal mechanism l.jpg

Causal Mechanism?

International business conditions: prices and salaries increasing everywhere

Ministers’ salaries

Price of rum


Popular study smoking causes bad grades l.jpg

Popular Study: Smoking causes bad grades

  • True or spurious?

  • What could be the variable (or variables) that drive both?


News reports l.jpg

News reports

  • Bottled water causes healthier babies

  • Drinking tea makes you less likely to contract lung cancer


Research question does education cause political tolerance l.jpg

Research question: Does education cause political tolerance?

  • Many scholars have found a positive relationship between political tolerance (support for liberty for political enemies) and education.

  • Causal mechanism?

    • As people are educated, they are introduced to different kinds of people and perceived danger of political enemies decreases.

    • As people are educated, they are socialized to the correctness of constitutional rights.


Alternative explanation l.jpg

Alternative Explanation

  • Political tolerance is actually caused by cognitive sophistication, as measured by IQ.

  • Causal mechanism?

    • It is difficult to reconcile the emotional reaction to named political enemies (i.e. Nazis) with constitutional rights and it takes a high IQ to understand that democracy benefits from giving liberties to “bad people.”


Slide10 l.jpg

Relationship between Education and Political Tolerance

High

Political Tolerance

Medium

Low

Low

Medium

High

Education


Slide11 l.jpg

Relationship between Education and Political Tolerance

High

Political Tolerance

Medium

Low

Low

Medium

High

Education


Controlling for iq l.jpg

Controlling for IQ

  • X = high IQ

  • Y = low IQ


Slide13 l.jpg

Education and Political Tolerance

High

Political Tolerance

Medium

Low

Low

Medium

High

Education


Slide14 l.jpg

Education and Political Tolerance - High IQ

High

Political Tolerance

Medium

Low

Low

Medium

High

Education


Slide15 l.jpg

Education and Political Tolerance - High IQ

High

Political Tolerance

Medium

Low

Low

Medium

High

Education


Slide16 l.jpg

Education and Political Tolerance - Low IQ

High

Political Tolerance

Medium

Low

Low

Medium

High

Education


Slide17 l.jpg

Education and Political Tolerance - Low IQ

High

Political Tolerance

Medium

Low

Low

Medium

High

Education


Conclusion l.jpg

Conclusion?

  • What was the hypothesis?

  • What was the alternative explanation?

  • What do we conclude about the likely cause of political tolerance?


Review l.jpg

Review

  • A spurious effect is a specific case when correlation is not causation.

  • The specific case is related to whether the two things correlated are caused by a third variable.


An illustration with a causal model l.jpg

An illustration with a causal model

A and B are spuriously correlated if:

Z

B

A


A test of whether a and b are spurious l.jpg

A test of whether A and B are spurious

  • Look at the relationship between A and B, controlling for Z

  • This means, that for all values of Z, you should look at the relationship between A and B.


Crosstab analysis testing for spurious relationships part i z 1 or 2 l.jpg

Crosstab analysis testing for spurious relationships, part I (z = 1 or 2)


Crosstab analysis testing for spurious relationships part 2 z 1 l.jpg

Crosstab analysis testing for spurious relationships, part 2 (z = 1)


Crosstab analysis testing for spurious relationships part 3 z 2 l.jpg

Crosstab analysis testing for spurious relationships, part 3 (z = 2)


Scatterplot illustration of a spurious relationship l.jpg

Scatterplot illustration of a spurious relationship

Z = 1 or 2

A

Z = 1

B

Z = 2

A

A

B

B


  • Login