# errors

1. ### External Model Validation

Trying to get some input on my below process/method to validate a prediction model! I have a sample of 200 peoples' dependent variable (positive continuous lab value) and days since an exposure (independent value). I fit a GLM with dist=gamma and link=log. From this I get a model coefficient...
2. ### Derive an equation for the relative error of V if the errors of c1 and c2 are known

Hello, I am having a problem figuring out a solution to the following and would be very grateful if anyone can help: Different concentrations c1 and c2 of an ion of charge q across a cell membrane lead to a voltage difference V , where V=(kT/q)*ln(c1/c2) Derive an equation for the relative...
3. ### Errors on fit parameters with no errors on data

Hi all Many, maybe all, statistical packages I know of (R, matlab, root, sas) will allow you to fit data with no associated errors, and give you back fit paramters with errors. How is that possible? Many fit libraries use some form of maximum likelihood, e.g. minimizes chi squared or least...
4. ### Compensating errors; normal distribution; subset; monte carlo simulation

Hi all, Please forgive the slightly long winded explanation, I could really do with some help here. I have a computer simulation which contains multiple variables to which I have applied random perturbations in order to simulate the possible error. The random perturbations are in the form...
5. ### Heckman SPSS error

HI: I was trying to download the heckman command and I believe I managed to do it. It's available now on the menu analyze/regression/heckman However, when I try to run I always get this error message: "Error in dirname(fpath) : a character vector argument expected" Anyone know what it...
6. ### Teacher of elem gifted kids looking for resources

Greetings! I teach math and science to gifted 5th and 6th graders. We recently read "Scammed by Statistics" by Ed Zaccaro (what a great book!) where my students learned a LOT about different ways that people misuse statistical information. I am looking for origianl examples of bad...
7. ### Idea (probably not new) about a metric for comparing forecast errors across settings

Hi there, I had written a large post, but was kicked off upon submitting, so I will keep this post to minimum... What are your views of the following metric for comparing the forecasts of different forecasters working in very different settings: |actual - forecast| / standard deviation...