Designing Social Inquiry week 4

I36005 Soohyung Ahn

Case Study1936 PRESIDENTIAL ELEC-TION : Roosevelt VS

Landon

Question?

• In 1936, FDR, completing his first term of office as president of the US, was running against the Republican candidate, Alf Landon of Kansas. The Literary Digest magazine, in a poll consist-ing of about 2.4 million individuals, the largest in history, predicted a victory for Landon by 57 percent to 43 percent. Despite this decisive prediction, Roosevelt won the election by a huge landslide – 62 percent to 38 percent. Why do you think Literary Digest failed so dramati-cally?

Contents 1.Background situation2.The sampling frame used by The

Literary Digest3.Why did this magazine fail to pre-

dict?4.George Gallup’s prediction5.Conclusion

Background • In 1936, presidential elec-

tion: Roosevelt vs. Landon• The Literary Digest

conducted every presidential election poll from 1916 to 1938.

• Sample size: 2.4 million out of 10 million.

• They predicted Landon would win by 57%

• Election result: It was a land-slide for Roosevelt by 62%

Why did The Literary Digest have great suc-cess in its prediction accuracy prior to

1936? (The sampling frame used by The Literary Digest)• It was a famous and popular magazine that suc-

cessfully predicted the outcome of the presiden-tial election for many years.

• It used the unscientific straw poll to gauge public opinion and to predict the popular vote.

• It also used national straw polls in 1920, 1924, 1928 and 1932, and it guessed the winner of each presidential election.

• “Uncannily accurate”

Background (cont’d)

Actual result of Election

The Literary Digest Poll was bi-ased!

• Selection bias- The owners of autos and telephones- Lists of magazine subscribers (wealthy people)- Automobile and telephone lists were not representative samples- Roosevelt’s supporters were excluded (the poor)

• Timing- The ballots were mailed in early September.(the returns were published each week from 6 September to 31 Octo-

ber.)- The Great Depression

• Nonresponse Bias- Low response rate (2.4 million out of 10 million.)- Do Republicans live nearer mail-boxes than Democrats?

A Landmark in Research HistoryThe Literary Digest

Poll

• It predicted Landon as next president.

• The Literary Digest was out of business the following year. 

• Straw polls started in 1824.

• Straw poll 

The Gallup Poll• George Gallup founded the

American Institute of Public Opinion in 1935.

• It predicted Roosevelt.• Gallup used a random poll

sample of 50,000 people.• He said: Literary

Digest would get it all wrong, despite the Digest’s decent track record in previous polls.

• Random sampling

Conclusion• Sample size is not a critical issue! • It is important to reduce sample bias!• Watch out the nonsystematic elements,

tend to overwhelm or distort the systematic element.