- CFA Exams
- CFA Level I Exam
- Topic 1. Quantitative Methods
- Learning Module 7. Estimation and Inference
- Subject 1. Sampling Methods
CFA Practice Question
A systematic sampling method should not be used when ______
A. the data are systematically biased.
B. the data are divided into open-ended classes.
C. the data are already arranged in the form of a predetermined pattern.
Explanation: If the data are already arranged in the form of a predetermined pattern, using systematic sampling can introduce a systematic pattern in the sample itself, which would lead to erroneous inferences about the entire population.
User Contributed Comments 4
| User | Comment |
|---|---|
| ljamieson | And that is why random sampling should always be used! |
| chamad | What's systematic sampling? |
| jpducros | Good question chamad...apparently systematic sampling would consist in selecting every kth member from a population, where k, the sampling interval (sometimes known as the skip) is calculated as k= N/n where n is the sample size and N is the population size. Ex : From a population of 120 item, you want to sample 8 items. 120/8=15, so every 15th item is chosen, after a random starting point between 1 and 15. If random starting point is 11, then the item selected are 11,26,41,71,86,101 and 116. |
| Jurrens | think of a new deck of cards that hasn't been shuffled yet... |