During the Last Few Days Before a Presidential Election, There $Y$

question 40

Essay

During the last few days before a presidential election, there is a frenzy of voting
intention surveys.On a given day, quite often there are conflicting results from three
major polls.
(a) Think of each of these polls as reporting the fraction of successes (1s) of a Bernoulli random variable $Y$ , where the probability of success is $\operatorname { Pr } ( Y = 1 ) = p$ . Let $\hat { p }$ be the fraction of successes in the sample and assume that this estimator is normally distributed with a mean of $p$ and a variance of $\frac { p ( 1 - p ) } { n }$ . Why are the results for all polls different, even though they are taken on the same day?

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Definitions:

Methodologies

Denotes the systematic, theoretical analysis of the methods applied to a field of study or the theoretical analysis of the body of methods and principles associated with a branch of knowledge.

Epidemiological Studies

Epidemiological studies are research investigations that examine the patterns, causes, and effects of health and disease conditions in defined populations.

Incidence

The occurrence, rate, or frequency of a disease, crime, or something undesirable within a specified population or area.

Prevalence

The proportion of individuals in a population who have a particular disease or condition at a specific time.