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- Topic: Confidence Intervals - Which Test?
| Author | Topic: Confidence Intervals - Which Test? |
|---|---|
| GeorgeC @2009-12-19 09:41:35 |
Could someone just confirm whether or not the z score is ok to use when sample size is >=30 when the population distribution is not normal and the variance is unknown? I know t can be used but is z just as acceptable or should it always be t? Thanks |
| gelar005 @2010-01-19 14:44:33 |
If the population is normally distributed, and the population variance is known, use a z-score irrespective of sample size. If the population is normally distributed, and the population variance is unknown, use a t-score irrespective of sample size. If the population is not normally distributed, and the population variance is known, use a z-score only if n >= 30, otherwise it cannot be done. If the population is not normally distributed, and the population variance is unknown, use a t-score only if n >= 30, otherwise it cannot be done. |
CFA Discussion Topic: Confidence Intervals - Which Test?
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