http://www.ck12.org Chapter 2. Visualizations of Data
Here is a similar set of data given in pounds.
TABLE2.29:
Material Pounds
Plastics 13. 7
Lead 3. 8
Aluminum 8. 4
Iron 12. 2
Copper 4. 7
Tin 0. 6
Zinc 1. 3
Nickel 0. 5
Barium 0. 1
Other elements and chemicals 14. 2The source of this data set was in India, so like much of the rest of the world, the data was given in metric units,
or kilograms. If we want to convert these weights to pounds, what would be different about this distribution? To
convert from kilograms to pounds, we multiply the number of kilograms times 2.2. Think about how, if at all, the
shape, center, and spread would change. If you multiple all values by a factor of 2.2, then the calculation of the mean
would also be multiplied by 2.2, so the center of the distribution should be increased by the same factor. Similarly,
calculations of the range, interquartile range, and standard deviation will also be increased by the same factor. So
the center and the measures of spread will increase proportionally. This should result in the graph maintaining the
same shape, but being stretched out or elongated. Here are the side-by-side box plots for both distributions showing
the effects of changing units.