- CFA Exams
- CFA Level I Exam
- Topic 1. Quantitative Methods
- Learning Module 7. Estimation and Inference
- Subject 1. Sampling Methods
CFA Practice Question
What are the reasons for sampling?
Correct Answer: Sampling is used when:
2. There is a limited amount of time available.
3. The nature of the test is destructive.
4. The cost of gathering the data is a factor.
1. The population is infinite.
2. There is a limited amount of time available.
3. The nature of the test is destructive.
4. The cost of gathering the data is a factor.
User Contributed Comments 8
| User | Comment |
|---|---|
| chamad | would someone elaborate point 3? |
| JimM | If the measurement destroys the item being measured (for example, measuring the purity of a manufactured chemical tested by burning it and analyzing the components of the gases released, something I used to do), then it is better to make the measurement on a sample than on the whole population. What if someone wants to check your results and there's nothing left to test? Or, if the items are meant to be sold, there's nothing left to sell if it's all be destructively tested. |
| robB | There was a tennis ball example in the notes as well |
| fmhp | What is a test? |
| 2014 | complete study of a subject is test |
| johntan1979 | JimM nailed the explanation of point 3. Another example is crash test of newly manufactured cars. You HAVE to sample, because if you don't, you have to crash ALL the cars manufactured to obtain crash test results :) |
| denisw123 | Or the population is just extremely large, doesn't have to be *infinite* |
| greglong1 | CTE in football players can only be diagnosed by brain autopsy. We can't dissect the brains of all NFL players to analyze the effects of repetitive concussions from playing football, so we have to rely on a representative sample of those who have already passed. |