Biology 2244A/B Chapter Notes - Chapter 19: Standard Deviation, Confidence Interval, Statism
25 Dec 2016
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To do inference about a population mean, u, we use sample mean, x| Same reasoning of sampling distribution of x| replacing means with proportions. Parameter p: proportion of people who are successes in the population. Behaviour of p^ is similar to behaviour of sample means, x| When sample size n, large: sampling distribution is approximately normal. Mean of sampling distribution of p^: the true value of the population proportion. P^ is unbiased estimator: of population proportion p. Gets smaller as n, sample size gets larger. Estimation more likely to be accurate when sample is larger. Need 4x as many observations to cut standard deviation in half, as it is only inversely proportional to the root of the sample size. When p is close to 0 or 1. Sampling distribution of p^: is close to normal. Critical value: chosen to cover the central area, c, under the standard. We can replace standard deviation with standard error of p^
