The statistic known
Storyboard Text
- To determine the appropriate tool when variance is known, using Z-test. Oops! Wait, someone know what is Z-test mean? If none, a Z-test is a statistical test used to determine whether two population means are different when the variances are known and the sample size is large.
- HOW TO DETERMINE THE APPROPRIATE TOOL WHEN VARIANCE IS UNKNOWN?
- How about variance is unknown? let me tell you. Do you hear the t-test guys? No, right? okay, a t-test is an inferential statistic that is used to see if there is a significant difference in the means of two groups that are connected in some way.
- HOW TO DETERMINE THE APPROPRIATE TOOL WHEN VARIANCE IS UNKNOWN?
- t-test is appropriate tool used when:~The population standard deviation (σ) is unknown. ~The sample standard deviation (s) is known.~The population is normal or nearly normally distributed.~The sample size is less than 30 (n30).
- REMEMBER
- How about the the Central Limit Theorem? Do you know what it means guys? okay then CLT is used, by replacing population standard deviation () with sample standard deviation (s) in the formula, the relevant test statistic is z-test.
- HOW TO DETERMINE THE APPROPRIATE TOOL WHEN: CENTRAL LIMIT THEOREM
- REMEMBER
- Z-test is the appropriate tool to used in central limit theorem when:If the population is normally distributed or the sample size is large and the true population means μ = μo, the z has a standard normal distribution.The sample size is extremely large and the variance (σ2) is known or unknown.The sample standard deviation (s) may be used as an estimate of the population standard deviation (σ) when the value of σ is unknown.
- Z-test ~ n ≥ 30, σ is known ~n ≥ 30, σ is unknown (Central Limit Theorem)~n 30, σ is known
- That concludes our lesson for today. Thank you for your time. And I hope to see everyone at our next meeting. Hello, class!
- T-test~n 30, σ is not known~n ≥ 30, s is known
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