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  1. noetsi

    sampling

    yes I am doing a survey. I was wondering if the number used to calculate the error was tied to how many you send out or how many you get back. As I guessed it is the number you get back. We have areas that make up our statewide numbers. I was asked if you had to sample at the area level (so...
  2. noetsi

    sampling

    I know the general theory on finding out how many you need for an error range. But I have some questions I had not seen or forgot. What if you population is limited. We have a population that, depending on how they define it, might be as few as 40,000. Does it matter if the population is a...
  3. noetsi

    Basic stat question

    Any general linear model, t-test, regression, ANOVA etc probably would work.
  4. noetsi

    should my model include separate predictors?

    Or SEM time based models or an ANOVA model with a time factor depending on what you are testing. There are many options.
  5. noetsi

    Does my predictor in my multiple regression have too many variables?

    In theory you should build models on theory. Most of us are not so lucky to have that. LASSO is better than stepwise (which is wrong, the use of stepwise that is if all to common). If you want to reduce the number of predictors LASSO or adapted LASSO is preferable - again assuming you have no...
  6. noetsi

    What is difference between Student's t test and Chow test?

    The chow test in time series is used to test if there is a structural break I believe.
  7. noetsi

    Useful R packages

    The irony is I have pretty much total permissions in SAS including building permanent tables that are housed on our server (but not the SQl server). That is why I do some long term projects in SAS using Proc SQL. Because I can build permanent tables there and views which I can not on the SQL...
  8. noetsi

    Calculate parameter estimate for reference level

    Couldn't you write a Contrast statement to do this? I don't do this type of statistics, and don't use glimnix as a result, but I would look at these statements and see if they help.
  9. noetsi

    Useful R packages

    thank you. We have limited permissions to the microsoft server where our SQL is housed. But maybe we will be able to use this.
  10. noetsi

    Useful R packages

    Everyone knows that I am learning R finally. :p I was curious what are some good R modules for beginner's. Simple regression is likely to be as complex as I will use. Graphical packages (for someone who will never be a master programmer) or things that interact with SQL would also be nice.
  11. noetsi

    R-squared is too high

    In fact real data that moves in time compared with real data that moves in time can generate extremely high R squared values. That is how you know there is a problem. Time is highly correlated with itself and that is what you are measuring. Not anything substantive. That is why time series...
  12. noetsi

    R-squared is too high

    It is what one would expect when correlating two series that are moving in time. You are correlating time with time.
  13. noetsi

    ?data analyst == statistician?

    Again in my unit the data analyst are all SQL people who do no statistics. I think meeting someone who has a PHD in statistics is pretty much, except at a University and a handful of government agencies, the same probability as meeting a Siberian Tiger. And that counts doctorates in Psychology...
  14. noetsi

    I cant hack it..

    I am not sure what the point of this thread is anymore.
  15. noetsi

    R-squared is too high

    If two time series, that is two data sets are moving in time and you don't address that you will get absurd R square values that mean nothing. That is the point I was trying to make earlier. There are no simple solutions for that unfortunately. I don't even pay attention to R square. I don't...
  16. noetsi

    ?data analyst == statistician?

    Data analyst in many organizations are likely SQL people as in my unit. Their salaries are pretty decent.
  17. noetsi

    Interpreting regression

    I have read many regression articles over the years (books as well) and the one thing that always puzzles me is the best way to interpret the results? I know slopes and odds ration (and the various measures of the model overall value ) and in honesty they seem pretty limited. I was wondering...
  18. noetsi

    R-squared is too high

    It is possible that you are conducting an analysis on two variables that are both moving in time. That can generate artificially high slopes and I assume R values. I think, although I have not personally encountered this, that having too many predictors relative to your sample size might also be...
  19. noetsi

    What is difference between Student's t test and Chow test?

    There are multiple uses and types of t test that make different assumptions. So you have to be careful when you talk about a t test. Some test single populations, some test if two populations are essentially the same, some pool data and some do not.
  20. noetsi

    ?data analyst == statistician?

    To me personally a data analyst is someone doing analysis that lacks the understanding of the math behind what he does. That is precisely what I am. I have lots of related degrees, but none focused on the math. I am not smart enough to do the math in honesty. :p I am not sure what a real...