Why did the famous 1936 literary digest straw poll fail to predict the number of the presidential election?

Answer 1

Although it had previously accurately predicted the winners of elections, The Literary Digest failed to do so in the election of 1936. The main reason was the method of polling they used. The polled their readers, who were wealthy enough to still be able to afford to buy the magazine during the depression. They also polled automobile and telephone user, who at that time would have been affluent. As a result, they did not tap into the pulse of America.
Respondents intentionally lied about their preferred candidate
Back then, polling and political science research were still very new, and not as reliable as they are today. Literary Digest did a mail-in poll, based largely on people who subscribed to their magazine. As it turned out, many of their subscribers were Republicans, and they did not want President Roosevelt (a Democrat) to win. But as anyone who has done survey research knows, a sample must be RANDOM in order to be reliable. Thus, selecting only your readers is great if you want research on opinions about your magazine; but if you want opinions about the election, you need to reach out to a much wider range of people, and have a variety of ages, races, various geographical locations, various political viewpoints, etc. Literary Digest did not do this; that is one big reason why their results were wrong.

Another reason is that asking people to mail in the reply (called "self-reporting") gets you only those people who are called "actives"-- they are passionate enough about the subject to send you a letter, fill out a survey, answer questions, etc. To get a good sample, you need "passives"-- they make up the majority of the public, and they rarely send a letter or fill out a survey, even though they do have opinions. You need reach out to them, and Literary Digest did not do this. They only got results from the most passionately political people, who make up about 7-10% of the average audience. This was another reason their results were so wrong.
The Literary Digest only polled its subscribers, who were wealthier than most Americans, and therefore tended to have a more negative view of some of Roosevelt's policies. FDR won the election with 60. 8 percent of the vote.

Answer 2

It failed to connect with poor voters.

Answer 3

It failed to poll the poor.