
z or t test ANOVA
I have a question about when I should use what...
ln (p/1p) = B0 + B1 * age + B2 * civil status
n=100
Show with a statistical test that/if age and civil status affect the outcome of y.
B SE
Age 0,0632 0,0196
Civil status 0,0427 0,4545
Constant 2,8190 0,9335
So my question is if I should use a or b
a) z=B/SE =0,0632/0,0196=3,22 3,22>1,96 can show that it effects
=0,0427/0,4545=0,094 0,094<1,96 cant show that it effects
H0: B1=o B2=0
H1: B1≠0 B2≠0
b) t=b1B1/sb1 =0,06320/0,0196=3,22
=0,04270/0,4545=0,094
tkrit= ?
Thanks in advance!!! :)

Re: z or t test ANOVA
Hi emme1! :)
This is a multiple linear regression where you test the individual coefficients with a ttest.
Btw, ANOVA is not involved (there are no variances that are being analyzed).
For the first coefficient, you have:
H0: B1=0
H1: B1≠0
It's a tdistribution with n3=1003=97 degrees of freedom (generally df=np1, where p is the number of parameters).
You get (slight modification of what you wrote):
t=(b10)/SEb1=0,06320/0,0196=3,22
Assuming an alpha of 5%, your critical tvalue is t*=1,98.
(As you can see this is quite close to the 1,96 critical zvalue you already had.)
Since t = 3,22 < 1,98, it follows that H0 can be rejected.
So yes, age has a significant effect on the outcome.
The method for the other coefficient is the same.

Re: z or t test ANOVA
Thanks a lot!!
and thank you for helping me with the df!
I just got the "correct answer" and they used the ztest.
hmm... When do you use the ztest like I wrote above?

Re: z or t test ANOVA
Hmm, the critical difference between a ttest and a ztest is knowledge about the standard deviation of the population parameter.
Wait, I'm just realizing that you are apparently testing proportions.
That is something that can be treated as having a known standard deviation.
The point being that the corresponding binomial distribution can be approximated by a normal distribution with a standard deviation that can be calculated.
To be honest, I'm not exactly sure of all the details, but it might be okay to do a ztest then.
Btw, as you've already seen, it matters not at all.
The critical values are very close, and the scores are way different.

Re: z or t test ANOVA
True!
So I guess both ways are correct?
I have seen both, but I just assumed that one of them was wrong... it's tricky :)

Re: z or t test ANOVA
From a practical point of view, both are just fine.
From a theoretical point of view, you should take a look at your notes, or your book.
It probably contains a worked example or something that shows exactly how you're supposed to do it... for a logistic regression in multiple variables.
(I'd tell you, but wikipedia does not appear to contain all the details.)