An insecticide company exposes 10,000 cockroaches to its newest product, and exposes another 10,000 to their previous formula. The researchers use videotape to count how many cockroaches are still alive, and how many appear to be in distress, at 10 second intervals. When the test is completed, the researchers determine the mean elapsed time before a cockroach was killed by each product.

Question

An insecticide company exposes 10,000 cockroaches to its newest product, and exposes another 10,000 to their previous formula. The researchers use videotape to count how many cockroaches are still alive, and how many appear to be in distress, at 10 second intervals. When the test is completed, the researchers determine the mean elapsed time before a cockroach was killed by each product.

I. What is the population?
II. What is the sample?
III. Is the study observational or experimental? Justify your answer.
IV. What are the variables?
V. For each of those variables, what level of measurement (nominal, ordinal, interval, or ratio) was used to obtain data from these variables?

Answer 1

I. The population in this scenario would be all cockroaches.

II. The sample would be the 10,000 cockroaches exposed to the newest product and the 10,000 cockroaches exposed to the previous formula.

III. The study is experimental because the researchers purposely expose the cockroaches to different insecticides and observe the effects.

Justification: In an observational study, the researchers would simply observe the cockroaches without intervening or manipulating any variables. However, in this case, the researchers intentionally expose the cockroaches to different insecticides, making it an experimental study.

IV. The variables in this study are:
- Type of insecticide (newest product vs. previous formula)
- Number of cockroaches alive
- Number of cockroaches in distress
- Elapsed time before a cockroach is killed by each product

V.
- Type of insecticide: Nominal level of measurement was used because it represents categories or labels without any inherent order.
- Number of cockroaches alive: Ratio level of measurement was used because the variable can take any positive whole number and has a clear zero point (no cockroaches alive).
- Number of cockroaches in distress: Ratio level of measurement was used for the same reasons as above.
- Elapsed time: Interval level of measurement was used because the variable represents a continuous quantity of time and does not have a true zero point (time can go on indefinitely).