Estimating Population Measures of Center

Student Summary

Some populations have greater variability than others. For example, we would expect greater variability in the weights of dogs at a dog park than at a beagle meetup.

Dog park:

A picture of 2 small dogs, 2 medium sized dogs, and 3 large dogs.

Mean weight: 12.8 kg       MAD: 2.3 kg

Beagle meetup:

A picture of 7 similar sized beagle dogs.

Mean weight: 10.1 kg       MAD: 0.8 kg

The lower MAD indicates that there is less variability in the weights of the beagles. We would expect that the mean weight from a sample that is randomly selected from a group of beagles will provide a more accurate estimate of the mean weight of all the beagles than a sample of the same size from the dogs at the dog park.

In general, if samples from a population have similar sizes, a sample with less variability is more likely to have a mean that is close to the population mean.

Visual / Anchor Chart

Standards

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