The Literary Digest - Wikipedia
“President” Landon and the Literary Digest Poll. Article in Social Science History Why did the Digest poll fail so miserably? One view has come to prevail . and important blocs of voters. The only the Gallup Poll became promi- nent during the presidential election, scholars .. “Why the Literary Digest Poll Failed,” Public Opinion Quarterly 52 .. However, while significant relationships were. by the Literary Digest poll is a landmark event in the history of American survey research in reiterated his version of the failure of the Digest poll. It is also important that its pedigree can be traced back to such an authority .. Erikson, Robert S. () “The relationship between public opinion and state policy: A.
We discuss this next. Non-response bias People who have been randomly selected to be part of a survey but refuse the invitation to participate can be different from the people who agree to participate. Non-response bias occurs when the people who respond to the survey are different, on average, from those who do not. More generally, the units in a sample that cannot be contacted and the units in the sample that can be contacted may differ in important ways that relate to the purpose of the survey.
Often, unfortunately, the possibility for non-response bias is ignored. The lower the response rate, the more scope there is for non-response bias.
If a large proportion of a sample fails to respond, having a large sample will not help: Exercise 5 Consider carrying out a long-term study of drug and alcohol use in young men, where you select a random sample of boys aged 13 to 16 and intend to follow them up several times into adulthood. How might you select the sample of boys? What issues might arise in following these adolescents over time? Might these issues relate to the outcome we are interested in?
What kind of biases might this introduce? Example There was a state election in Victoria in late On 12 NovemberThe Age reported the outcome of an online poll they conducted. There were three main parties in Victoria at the time: In the poll, the percentage of respondents indicating that they would vote for Labor was two-thirds of those saying they would vote for the Greens, that is, considerably less.
Content - How biases can arise in sampling
Exercise 6 Consider the The Age poll on voting intentions in the Victorian election. In the actual election, the vote for Labor was more than three times greater than that for the Greens.
There were over 27 respondents to the poll. Is that enough for it to be reliable?
Who was likely to have access to this poll? Who was likely to respond? Why was there a disclaimer? The purpose of both polls was to provide accurate estimates of the percentage of people voting for Roosevelt and for Landon. The voters responding to The Literary Digest's invitation to participate, in particular, tended to be Republican Landon voters; those who chose not to participate tended to be Democrat voters. Biases in the same direction are likely to have been operating in Gallup's pre-election poll, as his result underestimated the Democrat vote.
Scholars still debate the extent to which the spectacular failure of the Literary Digest poll was due to non-response bias versus a biased sample frame. It is likely that both were contributing factors. Exercise 7 The Literary Digest's presidential poll of obtained responses from 2 voters from 10 sampled. If the poll was unbiased, what percentage vote for Roosevelt is predicted?
We wired him as follows: For nearly a quarter century, we have been taking Polls of the voters in the forty-eight States, and especially in Presidential years, and we have always merely mailed the ballots, counted and recorded those returned and let the people of the Nation draw their conclusions as to our accuracy. So far, we have been right in every Poll.
Will we be right in the current Poll? Farley, Chairman of the Democratic National Committee.
Statistics, Politics and Policy
This is what Mr. Farley said October 14, I consider this conclusive evidence as to the desire of the people of this country for a change in the National Government.
The Literary Digest poll is an achievement of no little magnitude. It is a Poll fairly and correctly conducted. On a similar occasion we felt it important to say: In a wild year like this, however, many sagacious observers will refuse to bank upon appearances, however convincing.
As for The Digest, it draws no conclusions from the results of its vast distribution of twenty million ballots. We make no claim to infallibility. We know only too well the limitations of every straw vote, however enormous the sample gathered, however scientific the method.
It would be a miracle if every State of the forty-eight behaved on Election day exactly as forecast by the Poll. We say now about Rhode Island and Massachusetts that our figures indicate in our own judgment too large a percentage for Mr.
Landon and too small a percentage for Mr. Roosevelt, and although in the figures in these two States indicated Mr. We will not do the same this year; we feel that both States will be found in the Landon column, and we are reaching this conclusion by the same process that lead to the reverse conclusion in At the same time the Literary Digest was making its fateful mistake, George Gallup was able to predict a victory for Roosevelt using a much smaller sample of about 50, people.
This illustrates the fact that bad sampling methods cannot be cured by increasing the size of the sample, which in fact just compounds the mistakes. The critical issue in sampling is not sample size but how best to reduce sample bias. There are many different ways that bias can creep into the sample selection process. Two of the most common occurred in the case of the Literary Digest poll.
The Literary Digest's method for choosing its sample was as follows: Based on every telephone directory in the United States, lists of magazine subscribers, rosters of clubs and associations, and other sources, a mailing list of about 10 million names was created. Every name on this lest was mailed a mock ballot and asked to return the marked ballot to the magazine.
One cannot help but be impressed by the sheer ambition of such a project.
Nor is is surprising that the magazine's optimism and confidence were in direct proportion to the magnitude of its effort. In its August 22, issue, the Litereary Digest announced: Once again, [we are] asking more than ten million voters -- one out of four, representing every county in the United States -- to settle November's election in October. Next week, the first answers from these ten million will begin the incoming tide of marked ballots, to be triple-checked, verified, five-times cross-classified and totaled.
When the last figure has been totted and checked, if past experience is a criterion, the country will know to within a fraction of 1 percent the actual popular vote of forty million [voters]. There were two basic causes of the Literary Digest's downfall: