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- I doesn't know how can i present the topic Identifying appropriate test statistics involving population mean.
- Ohh! Let me help you.
- Hi Carl! why you look confuse?
- Ow that's nice but my question is what is the appropriate tool when the variance is known, variance is unknown, and when central limit is used
- It very basic. If the population standard deviation is known, then the mean has a normal distribution. We will use z-test, and when the variance is known and either the distribution is normal or sample size is large use z-test statistic
- For example, A principal at a school are above average intelligence. A random sample of 30 students IQ scores have a mean score of 112.5. The mean population IQ is 100 with a standard deviation of 15
- AS I RECALL, TEST STATISTIC IS A RANDOM VARIABLETHAT IS CALCULATED FROM SAMPLE DATA ANDUSED IN A HYPOTHESIS TEST
- Hmm... The sample size(n) is 30 and population standard deviation is 4.
- Now I know ! Can you give me another example?
- A statistics teacher wants to compare his two classes to see if they performed any different on the tests he gave that semester, Class a had 25 student with an average score of 70, standard deviation 15. Class B had 20 student with an average score of 74, standard deviation is 25.
- Great! and Because the population standard deviation is known and the sample size is greater than 30. The appropriate test statistic or tool to be used is Z-Test
- You are doing well john! I'm sure that you are ready with your presentation.
- AHA! Because the sample size is less than 30 which is 25 and 20 and the population standard deviation is 15 and 25. The appropriate test or tool is T-Test.
- When the value of the sample size(n)....Greater that or equal to 30 and the standard deviation is known and , use Z-TESTLess than to 30 and the standard deviation is unknown, use T-TEST.
- Thank you very much Gladys! Now i know what to do because of you.
- No worries Karl!
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