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Sampling Distributions and Statistic of a Sampling Distribution

25 四月, 2016 - 11:29
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You can think of a sampling distribution as a relative frequency distribution with a great many samples. (See Sampling and Data for a review of relative frequency). Suppose thirty randomly selected students were asked the number of movies they watched the previous week. The results are in the relative frequency table shown below.

# of movies

Relative Frequency

0

5/30

1

15/30

2

6/30

3

4/30

4

1/30

 

If you let the number of samples get very large (say, 300 million or more), the relative frequency table becomes a relative frequency distribution.

A statistic is a number calculated from a sample. Statistic examples include the mean, the median and the mode as well as others. The sample mean \bar{x} is an example of a statistic which estimates the population mean µ.