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  #1  
Old 07-31-2011
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Default Biostats

hey !

can someone explain this to me written on pg-55 FA 2011....

"if the 95% confidence interval for a mean difference between 2 variables includes 0 ,then there is no significant difference and null hypothesis is not rejected.."

anyone out there than can explain this to me!
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  #2  
Old 07-31-2011
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Imagine this scenario:

H0: A new treatment is not more effective than the traditional one
HA: A new treatment is more effective than the traditional one

The 4 options are:

1. Adopt the new treatment when in reality the new treatment is more effective = Correctly rejecting the null hypothesis - Power
2. Continue with the traditional treatment when in reality the new one is more effective = Type II Error - the event that the null is not rejected when the alternative is true
3. Continue with the traditional treatment when in reality the new one is not more effective = Correctly not rejecting the null hypothesis
4. Adopt the new treatment when in reality the new one is not more effective = Type I Error - the event that the null hypothesis is rejected when H0 is actually true

Now, in statistics, the test statistics is always under the null (H0):
1.- When we are talking about the difference in proportions between group A & B OR the difference in means between group A & B, our test statistic follows H0 = where the null value equals zero
2.- When we are comparing Odds Ratio/Risk Ratio, again our test statistic follows H0, but this time the null value would be equal to one (OR or RR = 1 under the null).


When we have 2 groups and we calculate a 95% CI for the diff. in means between groups

[-10,10] = the null value (null value = 0) is included in the CI = you fail to reject H0 (no difference)
[0.001, 10] = the null value (null value = 0) is not included in the CI = you reject H0


For more check here:
The Zero value in Confidence interval?
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The above post was thanked by:
alice (10-16-2012), heman466s (07-31-2011)
  #3  
Old 07-31-2011
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Quote:
Originally Posted by bebix View Post
Imagine this scenario:

H0: A new treatment is not more effective than the traditional one
HA: A new treatment is more effective than the traditional one

The 4 options are:

1. Adopt the new treatment when in reality the new treatment is more effective = Correctly rejecting the null hypothesis - Power
2. Continue with the traditional treatment when in reality the new one is more effective = Type II Error - the event that the null is not rejected when the alternative is true
3. Continue with the traditional treatment when in reality the new one is not more effective = Correctly not rejecting the null hypothesis
4. Adopt the new treatment when in reality the new one is not more effective = Type I Error - the event that the null hypothesis is rejected when H0 is actually true

Now, in statistics, the test statistics is always under the null (H0):
1.- When we are talking about the difference in proportions between group A & B OR the difference in means between group A & B, our test statistic follows H0 = where the null value equals zero
2.- When we are comparing Odds Ratio/Risk Ratio, again our test statistic follows H0, but this time the null value would be equal to one (OR or RR = 1 under the null).


When we have 2 groups and we calculate a 95% CI for the diff. in means between groups

[-10,10] = the null value (null value = 0) is included in the CI = you fail to reject H0 (no difference)
[0.001, 10] = the null value (null value = 0) is not included in the CI = you reject H0


For more check here:
The Zero value in Confidence interval?





i was expecting your answer!
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  #4  
Old 07-31-2011
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Quote:
Originally Posted by heman466s View Post
i was expecting your answer!
hahahaha....
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