Animal populations can be estimated using the capture-recapture method. The population size is estimated using the formula:
population estimate=number in first sample×number in second samplenumber of marked animals in second sample \text{population estimate} = \frac{\text{number in first sample} \times \text{number in second sample}}{\text{number of marked animals in second sample}} population estimate=number of marked animals in second samplenumber in first sample×number in second sampleSometimes, the animals become 'trap-happy' after the first capture because they associate the traps with easy food. This makes them more likely to enter the traps again for the second sample.
What effect does this behavior have on the population estimate?
The estimate is always too high.
The estimate is always too low.
The estimate is either too high or too low.
There is no effect on the estimate.