1 tail vs. 2 tail

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Usif

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ok silly question but i don’t understand why we determine the critical t value from the confidence interval assuming its one tailed..
I thought we always use two tail when looking up critical t-values..!?!
Consider the following estimated regression equation:
ROEt = 0.23 - 1.50 CEt
The standard error of the coefficient is 0.40 and the number of observations is 32. The 95 percent confidence interval for the slope coefficient, b1, is:
A) {0.683
B) {-2.300
C) {-2.317
D) {-3.542
 
The 5% one tail test will give you the same as the 2.5% two tail test.
 
Niblita isn’t it the other way around?
a 2.5 one test has same number as 5% two tailed test?
 
-1.5 +/- 2.042(.4)
Yea, I tried to do it off memory. It’s much easier looking at the table.
 
two tailed 2.5 is equivalent to one tailed 5 percent, because you are looking for the equivalent of 95 percent. in the two tailed, each tail has 2.5 percent of the total 5 percent outside of the confidence interval. In the one tailed, only one side, so it takes the entire 5 percent
 
always good to have some refreshers sundrani !!!
 
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