Question

Biologists studying the healing of skin wounds measured the rate at which new cells closed a cut made in the skin of an anesthetized newt. Here are data from a random sample of 18 newts, measured in micrometers (millionths of a meter) per hour: 29, 27, 34, 40, 22, 28, 14, 35, 26, 35, 12, 30, 23, 18, 11, 22, 23, 33. Create a QQ plot of the data. Do you think it is reasonable to assume that the population distribution is normal?

Answer 1

Explanation:

Hello!

The QQplot graphic is attached. This graphic is a probability plot used to determine the distribution of a sample. The X-axis has the theoretical quantiles for the normal distribution and the Y-axis represents the quantiles of the sample. The black line in the graphic represents the normal distribution for this population and the blue diamonds represent the sample values.

You compare the dots against the line to see whether the sample follows the theoretical values or not. If the values are dispersed respect the theoretical line, then you cannot assume that the population follows the normal distribution.

Now if the sample is closely related to the theoretical line, like the dots in the graphic, you can assume that they have a normal distribution.

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