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The stimulant ritalin has been shown to increase attention span and improve academic performance in children with adhd.
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To demonstrate the effectiveness of the drug, a researcher takes a sample of 20 children diagnosed with the disorder and measures each child's attention span before and after taking the drug.
00:17
We have a mean difference given to us of 4 .8 minutes and a variance, excuse me, a sample variance of 125.
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Is this result sufficient to conclude that ritalin significantly improves the attention span? so this is a one -tail test.
00:36
Our null hypothesis is that the mean difference is equal to zero.
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Our alternative is that the mean difference is greater than zero.
00:43
We're going to test at the 0 .05 level.
00:47
So t is going to be equal to 4 .8 minus zero divided by the square root of 125 over 20.
00:58
And that's 1 .95, or excuse me, 1 .92 with a p -value of 0 .0340.
01:07
So that p -value is less than alpha, so we are going to reject our null hypothesis...