DrS
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The intelligence quotient (IQ) scores are obtained for a sample of 100 patients diagnosed with various types of schizophrenia who completed a standard IQ test battery. An additional 20 patients had to be dropped from the sample because they lacked the functional capacity to complete two or more portions of the test. Four other patients refused to take the test battery when offered the opportunity. Results for the patients who completed the test battery gave an average IQ of 110 and a standard deviation of 20.
Using this information, compute the 95% confidence interval for this estimate of the mean.
A. 70 to 130
B. 70 to 150
C. 85 to 115
D. 90 to 130
E. 105 to 115
F. 106 to 114
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| robin082006
Forum Hero
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F
SE=20/square root of 100 = 2
At 95%, CI=mean+/- 2SE
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| robin082006
Forum Hero
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you should calculate standard error first and use it for CI calculation mavic.
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The Key to Succeed is Patience.
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| conma2cang
Forum Newbie
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finally i understand how to calculate CI.
thx robin.
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| HILFIGER
Forum Senior
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Agree with robin. However, I think that when we deal with a sample we should use estimated standard error and t score. I think CI=mean+/-2SE should suffice because it gives roughly the same result.
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