A Question of Scale
Backstory: In this chapter you learned how the scientific method can be used to answer important questions about the world around us. If used in a laboratory setting where all conditions, such as temperature, humidity, and light, can be controlled it is far easier to examine the effects of a single variable while holding others constant. In field studies, however, it becomes more difficult to assess a single variable due to the influences of other environmental conditions. The temperature inside an aquarium can be controlled easily in a lab setting, but how can temperature be controlled in an open system where so many other variables, such as cloud cover and solar angle, are constantly changing. Difficulties encountered in field research is further compounded by the need to choose the appropriate scale at which to capture the parameter being studied. Think about a one-meter square patch of grass in a field. If you counted all the different organisms in this small area, would this represent the entire field where it is located? The question of scale is also important in temporal analyses. The weather, for example, changes over time requiring scientists to determine what time scale will be effective in answering a specific question.
Activity: Demography examines human population size and structure. Age is a very important aspect of any population due to its inherent importance in reproductive rates of the population. Sometimes we need to know the average age of a subgroup of a population. We may, for example, want to compare the average age of students in one location in the country to another. We could perhaps better meet the needs of the students if we know their demographics. Another, sometimes more important, question is how big a range of ages are present. We may be better able to address age-related needs of the student population with this information.
The table below shows the estimated average ages of student populations, along with their ranges, for the top colleges and universities in the state of California, in Marin County, and in all of the United States. Enter data from your class into the chart below, and use the data to answer the following questions.
| Marin County | California | U.S. | Your Course | |
|---|---|---|---|---|
| Average age of students | 22 | 20 | 24 | |
| Range of students ages | 18–23 | 16–24 | 18–30 |
| Marin County | California | U.S. | Your Course | |
|---|---|---|---|---|
| Average age of students | 22 | 20 | 24 | |
| Range of students ages | 18–23 | 16–24 | 18–30 |
How do the student age averages and ranges in Marin County differ from the combined data for all colleges and universities in the state of California? How does the data for your course differ?
Why do you think they differ? Would other counties in California have the same statistics?
Why do you think there are differences in the average and range as you extend your scale to include a larger and larger population size?
How important is scale in studying the demography?
Activity results are being submitted...