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Sampling distribution alt text

The diagram is an output from iNZight Sampling Variation Module. There are 3 graphs, all with identical scales from 10 – 40 marked in 5s.

The top graph, labeled Population, shows a dot plot and a box plot of the population of 500 right foot lengths from the Census at School database. The grey dots are stacked in bars with an approximately normal shape, except the 24 cm bar is slightly lower than the 23 cm and 25 cm bars. Minimum is 10 cm, lower quartile is 22 cm, median 23 cm, upper quartile 25 cm, maximum 45 cm. There is a purple vertical line on the graph showing the mean of the population, labeled 23.43 cm. A light grey dotted line goes down from this mean through both the other graphs.

The second graph, labeled Sample, shows blue vertical lines very close together between about 23 cm and 24.5 cm and less dense from 22 cm to 26.5 cm. There are 1000 vertical lines, each representing a sample mean calculated from a random sample of 25 students from the population.

The third graph, labeled Sampling Distribution, shows the means of 1000 samples of size 25 from the population. It is approximately normally distributed with mean of 24.43 cm, lowest value 22 cm and greatest value 26.5 cm. This plot shows a sampling distribution of the sample mean.

Last updated September 25, 2013

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