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  1. noetsi

    When to control for a variable?

    You would want to control for a variable if theory says it is correlated with the dependent variable and your predictors. I assume PD is your dependent variable not a predictor. If gender is not related to another predictor then it is not a control in the way that is normally used. It is...
  2. noetsi

    Another confounding question. -ANCOVA and perhaps Regression

    As an aside you usually don't call variables confounds. A confound is something that is related to your dependent variable and also to one of your predictors normally and is distorting the relationship. When you control for that effect by placing a variable in a model it is normally called a...
  3. noetsi

    When to control for a variable?

    You don't confound for a variable, it either is a confound or is not :p You should base whether it is in the model or not based on theory (either your own or someone else's). I don't know what you mean by PD's but is sounds like you already have it in your model, if so it already is a control...
  4. noetsi

    Interpreting the COX Model

    What software are you using to generate this?
  5. noetsi

    SAS time series site.

    I found this very useful.
  6. noetsi

    Sample size for destructive testing

    I would guess something that is highly destructive does not have a lot of historical data :p
  7. noetsi

    Sample size for destructive testing

    If you could prove that every test is identical to every other test, including external events, you could do it. I am not sure that is realistic. If you are simply trying to show something will blow up, as with atomic bombs, and it does then one test is enough. But even nuclear weapons were...
  8. noetsi

    Autoregressive distributed lag model with different duration of lag

    I think that any software is going to have standardized lag for everyone. I don't think there is any way to tell it that a lag is two years [two periods] for one individual and three years for another. If you specify t+2 2 is going to be two periods [be the period years months or whatever]...
  9. noetsi

    Formatting in proc freq and proc sgplot

    the simple answer is you can if you can find a format that supports what you want to do. In honesty, I do my graphs in excel not SAS- SAS is a lot harder for me to use to do graphs. I use graphs in SAS to do analysis, but when I report anything I use excel. I have tried to do various thing in...
  10. noetsi

    Regression analysis with follow-up

    How is your dependent variable scored? On ordinal, interval or nominal data. How you do regression depends on this. If you are asking someone to assess themselves before and after some event then a test retest methodology (ANOVA) might be a way to go. Problems with bias of the rater is going...
  11. noetsi

    Time Series Data for Business Performance: Regression Model?

    If you mean you have only 18 independent months (that is 18 data points) than you don't want to do time series period. Among other problems its impossible to capture seasonality that way.
  12. noetsi

    Urgent Help:

    I don't understand this thread...
  13. noetsi

    none of the values of my results are significant. did I do something wrong?

    Getting all results insignificant does not mean you did anything wrong. It may mean none were significant. What was the statistical power of your analysis.
  14. noetsi

    Weigthed chisquare statistics

    I don't think there is a way to make a non-random sample random if that is what you are trying to do. I have never seen this even suggested.
  15. noetsi

    Time Series Data for Business Performance: Regression Model?

    I have tried to learn time series regression for 8 years and the best I can say is that there is no easy way to do this and no book that I would recommend to someone new to it. None of the forms of regression developed for it are simple. You might look for regression with ARMA error which is...
  16. noetsi

    Concept of Stationary Population in Demography.

    Actually I doubt that the probability of dying at a given age is the same over time in an advanced society. People live longer now than they did in say 1950 because of medical advances nutritional change etc. It is possible that people can only live so long genetically. Once you reached that...
  17. noetsi

    Does SAS run on Samsung Galaxy Tab S4 ?

    Sorry I don't know. I have never run SAS that way and am not an IT person (I am a data analyst). I suggest going to the SAS home page and sending them a question. This is technical support
  18. noetsi

    AIC and BIC values

    I have never been able to understand what a small sample is (the common response is "it depends"). My guess is 201 is not a small sample (given that by 30 z and t distributions are close and the central limit theorem kicks in, plus what samples I have seen in journals) but that is a wild guess.
  19. noetsi

    Selecting the first record for a particular variable based on a condition

    You likely could use PROC SQL as well limiting the data to those conditions that met your requirements.
  20. noetsi

    AIC and BIC values

    I think you would simply say which model had the lower scores, I doubt many will care what the specific values are. There is no clear rule as far as I know on how much a difference between AIC really matters. Note choosing based purely on AIC might not be ideal depending on what type of model...