FORESTRY
AGRICULTURAL STATISTICS AND ECONOMICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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1.65
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1.96
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2.58
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2.33
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Detailed explanation-1: -The Z value for 95% confidence is Z=1.96. [Note: Both the table of Z-scores and the table of t-scores can also be accessed from the “Other Resources” on the right side of the page.] What is the 90% confidence interval for BMI? (Note that Z=1.645 to reflect the 90% confidence level.)
Detailed explanation-2: -Z-scores are equated to confidence levels. If your two-sided test has a z-score of 1.96, you are 95% confident that that Variant Recipe is different than the Control Recipe.
Detailed explanation-3: -1.96 is used because the 95% confidence interval has only 2.5% on each side. The probability for a z score below −1.96 is 2.5%, and similarly for a z score above +1.96; added together this is 5%.
Detailed explanation-4: -Z is the standard normal random variable. The table value for Z is the value of the cumulative normal distribution. For example, the value for 1.96 is P(Z<1.96) = . 9750.