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Old 01-21-2012
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Stats 95% Confidence Interval includes a zero!

Hi I have a question on biostatistics and hope to get some help. On page 55 of FA for step 1 2011, top right corner, it says: If the 95% CI for the mean difference between 2 variables includes 0, then there is no significant difference and H0 is not rejected. Why?

Thank you for your help.

Sunny
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Old 01-21-2012
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H0 is not rejected means H0 is accepted. means null hypothesis is true.i.e there is no difference between whatever we were measuring.

if comparing two means for eg

the height of the students in a class
group A -130 132 134 136 170cm
group B -120 125 134 138 165cm

now take a mean difference between above two groups by subtracting each value of group A from group B. calculate the 95%CI which is CI=from [mean-1.96(SEM)] to [mean+1.96(SEM)] which is the range of around 2 SD on both sides of mean right !
if the mean diff between the 2 groups has a zero somewhere that means there is no diff between them. i dont know how to calculate the CI of mean difference exactly but just understand the concept.
if mean difference between two groups have a zero then there is no difference.so H0 will not be rejected and null hypothesis will be true i.e the 2 groups are not very different from each other.

the above eg is just trying to explain you. it may not be accurate.
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Old 01-21-2012
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Default Thank you.

I see. I understand the concept but somehow got confused by the wording. Thank you for explaining that to me.
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Biostatistics-Epidemiology, First-Aid

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