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T test

Statistics
by

Bent Neck

on 2 December 2012

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Transcript of T test

Z-Table Population Sample T table Df ( Degree of freedom ) = ( n - 1 ) 0.95 0.05 0.025 0.025 Mean T value Standard deviation Sample size T- Test When the Df increases the the value comes closer to the normal distribution In a population the average IQ is 100. A team of scientist wants to test a new medication to see if it has either a positive or negative effect on the intelligence, or no effect at all. A sample of 30 participants who have taken the medication has a mean of 140 with a standard deviation of 20. Did the medication affect intelligent. Alpha = 0.05 1.Defining the hypothesis
2.Calculation of the alpha level
3.Calculating the degrees of freedom.
4.State decision rule and the critical area
5.Calculate test
6.State results
7.State conclusions The Test procedure Q z test when the population standard deviation is know t - test is used when only the sample standard deviation is known _ Sample mean Sample std Sample size 2.045 -2.045 1.Defining the hypothesis H0 - µ = 100 ( No change in the results )
H1 - µ ≠ 100 ( there is a significant change in the results ) 2. Calculation of the alpha level Alpha level is given as 0.05 if not , by using the confidence level the alpha level can be calculated . 3. Calculating the degrees of freedom. n = 30

n = 30-1
= 29 4.State decision rule and the critical area Since , ..... We use Two tailed test 5. Calculating test EQUATIONS = 140- 100
20
√30

= 40
3.6514

=10.9544 6.State results and Stating conclusions Decision rule : is cal t was > o r < 2.045 rejecting the hypothesis cal t = 10.9544 there for the hypothesis is rejected . the drug proved to have made a significant difference in the IQ level = 100 ± 2.045
20
√30 x = 100 ± 7.467 = 92.533 - 107.467 The confidence level T test 95% Confidence level Therefor alpha = 0.025 The value for alpha 0.05, df -29 = 2.045 Df ( Degree of freedom ) = ( n - 1 ) When the Df increases the the value comes closer to the normal distribution Introduction Thats it :) If it was ...... BCAS !! Song Antartica - THUPPAKKI
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