METHODS OF DATA ANALYSIS
DECISION MAKING WITH HYPOTHESIS TESTING
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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When do you use a t-value instead of a z-value?
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When n < 30
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When n ≥ 30
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When all of the planets align
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When the teacher says so
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Explanation:
Detailed explanation-1: -A. A z-test is used to test a Null Hypothesis if the population variance is known, or if the sample size is larger than 30, for an unknown population variance. A t-test is used when the sample size is less than 30 and the population variance is unknown.
Detailed explanation-2: -If you have a sample which is large (a good guide is n≥30 n ≥ 30 ), then you can use a z-test.
Detailed explanation-3: -The t-distribution gives more probability to observations in the tails of the distribution than the standard normal distribution (a.k.a. the z-distribution).
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