standard error

Dear all, I have a model with three variables a dependent (dep), a binary independent variable (bin) and a contin. independent variable (con). I am basically interested in whether the effect of con on dep is heterogeneous with respect to bin. I regress...

why pooled Std err is bigger than the mean value of a group, when the sample size of three groups used in the analysis are different. Thanks.

Hi, I have the following problem: I want to draw confidence band for a quadratic regression I have the model: y=a+b*x+c*x^2, i have estimation for a,b and c together with their standard error. how do i draw the confidence band. i sort of understand their should be 2 formulas, one for...

Hello All, Just a little something I am unsure about, I hope you can help! So, If you have a pile of averages (say stem weight and root weight) and so you have two seperate standard errors. Now I want a standard error for the total weight, can I just add the two standard errors and have my...

Hi there, I have been trying to solve the problem below, but have had difficulties in solving it. I would really appreciate it if anyone could explain to me how to solve it. The standard deviation of the flow is s=0.3 occuring where the mean concentration is 0.9. The mean concentration is...

Hi folks, I'm hoping there's a straightforward answer to this (that isn't "no") :tup: For some data I know the mean, the upper and lower quartile figure, and also the number of observations on which it is based. I would like to know the standard error. Is there a way of working this...

Hi guys, I am new here (and also to statistics :o). I have a data set of many measurements. For each one of them I calculated the mean and the SD (deviation). From that I calculated separately for each of the data set a SEM. Now I would like to multiply, divide add and subtract this data...

Hi There, I have a commercial NET dll computing nonlinear regression coefficients and their sigma values. However, I would like to compute the confidence interval for each coefficient. I believe that I need to compute first the standard error for each coefficient, but if I use...

Hi, what exactly is the difference between the SD and SE? I read through the wikipedia article but dont really understand the difference. Can anyone help? Cheers beginner