### CFA Practice Question

There are 434 practice questions for this study session.

### 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 Comments4

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...