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  1. noetsi

    Removing terms from a model

    This comes from Harrell's book on regression. I am not sure I understand what he is saying (well that happens a lot). :p "From the above discussion a general principle emerges. Whenever the response variable is informally or formally linked, in an unmasked fashion, to particular parameters that...
  2. noetsi

    Missing data satisfaction research

    We have a motivation survey where say 75 percent of the individuals respond. If I understand this, this is not an issue of MAR/MNAR/MCAR. You have to make a judgement if you can generalize to the rest of the population, but this is not missing data in the sense multiple imputations would apply...
  3. noetsi

    Interaction effects

    I have a variable that has 4 levels tied to the type of disability. I have a theory that the type of disability influences the impact of services on income gains for customers. I am not sure of the best way to specify an interaction effect for this. Say spending is A, the original 4 level...
  4. noetsi

    Making an ordinal response variable binary

    I don't really understand why making an ordinal response variable binary is a bad thing. In fact having read logistic regression books I came to the conclusion that making an ordinal response variable binary was safer in terms of interpretation or violation of assumptions. "When the dependent...
  5. noetsi

    Strange package import error

    As far as I can tell the packages downloaded. But I get this strange error recently whenever I download anything. Error in unpackPkgZip(foundpkgs[okp, 2L], foundpkgs[okp, 1L], lib, libs_only, : ERROR: failed to lock directory ‘\\fldvr.net\hq\Users\rthellein\Documents\R\win-library\4.0’ for...
  6. noetsi

    Restricted cubic splines in R

    What is the simplest package to do cubic splines in R?
  7. noetsi

    Suppressing the confidence interval

    I am running the R package forecast. Only part of the code I ran is shown, I can't send the data and I don't think that matters for my question. modeltr<- Arima (mydatatr,order = c(0,1,1), seasonal= c(1,0,0)) > #forecast(modeltr, h=12) > forecast(modeltr, h=12) I only want the forecast not...
  8. noetsi

    Time series opinion

    There is no time series theory here. It is based on the opinion of some experts who do time series which has worked reasonably in the past for me. I have a data going back to 2014 by month. There were six models in the past all are ESM so the model structure for each in SAS is always the same...
  9. noetsi

    intermediate regression books

    I have read a lot of regression books that introduce the method, talk about assumptions etc. But I want to develop more advanced skills now. If it matters this is not about theory. I work in a social science organization and want to give advice based on the data. For example, what are key...
  10. noetsi

    Why do experts continue to use stepwise regression?

    There is extremely strong criticism of stepwise regression. But these experts use it in their method, and they are hardly alone. I don't understand this, I did not think there was much disagreement of stepwise. But from this article my sense if these are people who really understand...
  11. noetsi

    Wage project

    I am starting a new project and I want to get it right - it is the first we have run in many years and it covers a very important issue. I work for a public agency getting those with a disability jobs. Essentially we are looking at wages two quarters after people leave our agency as the...
  12. noetsi

    How do you know if X is moving Y in non-experimental data.

    Hey I got tons of points for this question on another board so it must be important right? Well it is extremely important to me who am a data analyst not a statistician. This is central to what data analyst who rarely have theory to build on (I have read a lot in my field, I have never seen an...
  13. noetsi

    Lasso regression

    I am trying to learn this and already I have several questions :p 1) Is it still true there is no (non bootstrap) way of generating SE for lasso? If so how do you do statistical test? 2) One article I read said that all variables had to be standardized to use bootstrap? Is that true? 3) I...
  14. noetsi

    Omitted variable bias

    I was concerned about unobserved heterogeneity originally, and read an interesting article by Jake on that. However, his article (much of which was beyond me) :p raised a question which is different and that seems to apply to linear regression as well as logistic regression although being worse...
  15. noetsi

    Relative impact

    My first question 11 years ago and I still cycle back to it every few years. I have a series of dummy predictor variables. I have a two level DV. I am running logistic regression. What I want to do is determine what variable has the greatest impact on the DV. Because we want to know what...
  16. noetsi

    Reference coding in SAS Proc Logistics

    I am doing reference coding and this confuses me. All my variables are dummy variables coded 1 and 0. This is the code PROC LOGISTIC DATA=WORK.SORTTempTableSorted PLOTS(ONLY)=ALL ; CLASS pd2 (PARAM=REF) pd1 (PARAM=REF) pd3 .....; MODEL DVD (Event = '1')=pd1 pd2...
  17. noetsi

    Missing data

    My great dread. I have a logistic regression There are 645 cases and data is missing in about 228. Only 6 did not answer the dependent variable the median missing for any predictor is 15 about 2 percent of the responses. The problem is there are 38 predictors and being missing on any causes you...
  18. noetsi

    Best way to run regression

    I have done this many ways in the past. I have a series of variables that are modeled on a four point likert scale from strongly disagree 1 to strongly agree 4. Originally, since I think it is reasonable the differences between the levels are the same, I ran linear regression using the raw...
  19. noetsi

    Simple effects estimate statement

    I am confused how to do this (generate the simple effect hours at a specific level of categorical variable prog). Note this is the same estimate statement substantively used by proc glm. proc plm restore = catcont; estimate 'hours slope, prog=1 jogging' hours 1 hours*prog 1 0 0, 'hours slope...
  20. noetsi

    What is interval

    This is what always confuses me about the term [I think they use the word continuous for interval] "effort: a continuous variable ranging from 0 to 50, which is an average of weekly subject-reported effort scores, also ranging from 0 to 50, with 0 denoting minimal physical effort and 50...