About VX_Xc

VX_Xc · ‎03-20-2012

How do I extract leading non zero digits? For example for .000212 I want to extract leading digit which is 2. and for 123.933 I want to extract leading digit which is 1. How do I do this? plz help

VX_Xc · ‎02-25-2012

Say I have a dataset below; country1 country2 transactions Korea USA 100 USA Korea 100 I would like to make a new variable with one paired value and sum transactions together, that is I want countrypair Total_trans Korea-USA 200 So that Korea USA pair is the same as USA Korea pair. I have 40 or so countries, and have to pair them like the example above. Is there anyway to do this other than having to specify each country? Thanks for your help

VX_Xc · ‎02-22-2012

Let's say something is updated in the web. Can SAS be hooked up so that it would automatically compute values?

VX_Xc · ‎02-22-2012

Can it?

VX_Xc · ‎02-21-2012

I'm still not sure what to do with your model but; I can help you with how to populate your dataset so that every state would have the same number of stores.(If you haven't already done so, sorry for the late reply.) Say you have a dataset called 'have' below; Obs store state value 1 1 1 10 2 2 1 10 3 3 1 10 4 4 1 10 5 5 1 10 6 1 2 20 7 2 2 20 8 3 2 20 proc transpose data= have out = have1; by state; run; data have2(drop = i); set have1; array c(5) col1-col5; * change 5 tonumber of columns; do i = 1 to 5; * change 5 tonumber of columns; if c(i) = . and _name_ = 'store' then c(i) = i; if c(i) = . and _name_ = 'value' then c(i) = 0; end; run; proc transpose data=have2 out = final(drop = _name_); by state; run; proc print data=final; run; Obs state store value 1 1 1 10 2 1 2 10 3 1 3 10 4 1 4 10 5 1 5 10 6 2 1 20 7 2 2 20 8 2 3 20 9 2 4 0 10 2 5 0

VX_Xc · ‎02-20-2012

With respect to what, are we maximizing the function? B?? What's model_input(x) ?? To find the optimal price, we first need to find supply and demand function. In your example we maximize sales (assuming wrt B) which would result in B going infinitiy even with the constraint that each store in a given state has to be the same. This is due to not specifying the demand function. once you estimated supply and demand function with constraint you can use Lagrangian functions to solve the problem using PROC NLMIXED or PROC NLP. I could come up with something if you would provide a sample of your dataset.

VX_Xc · ‎02-16-2012

Depending on the boxcox transformation you can interprete your predicted values in meaningful way. First log transformation of the regressors would result in interpreting coefficient as 1% change in a regressor results in \beta change in outcome variable. Now it depends on the transformation that was ultimately done to the outcome variable. as boxcox finds optimal power transformation you must look at at which power the outcome variable is transformed at. We just need to back transform it. for example if power transform was done at -1, and the confidence interval found for beta values are say .1 and .2 then the resulting interpretation would be that 1% change in the regressor results in change in y value by between 10 and 5 (which are inverse of .1 and .2). if power transformation was done at 1/2, then the CI for beta of 2 and 3 can be interpreted as 1% change in the regressor results in change in y value by between 4 and 9. and so on. OR I have totally misunderstood your question.

VX_Xc · ‎02-16-2012

In stepwise regression the decisions about which variables should be included will be based upon slight differences in their semi-partial correlation. This in turn leads to the danger of over or under fitting, which may contrast with theoretical importance of a predictor. Sounds intuitively appealling to have some procedure that automatically chooses the predictors(regressors) for you, however samples are not perfect. That is the statistical procedures assume that our sample data are perfect (no measurement error, omitted variable and stuff), hence the statistical significance obtained from the procedure assuming this perfect data will be biased(wrong). We must reason and use our brains to choose which regressors should be looked at (ideally we would want some theory to base our decision). Also step-wise procedures to choose which regressors were to be included depends on what regressors we have in our dataset. So if we do not have any theory on which regressors should be looked at and just used stepwise procedure to select regressors then people will conclude differently depending on the regressors they have in their data. I tend to think about stepwise procedure to be the best procedure to choose the regressors IF we have datasets with all possible variables in the world (billions and billions of them) and have the computing power that can go through these variables at multiples of lighting speed. Which is not possible now or in our life time.

VX_Xc · ‎02-16-2012

yeah because I added you. I'm VX=XC.

VX_Xc · ‎02-16-2012

Say you have a dataset named “have” below; Obs date quantity price totalprice 1 200001 10 5 50 2 200002 10 5 50 3 200003 10 5 50 4 200004 10 5 50 5 200005 10 5 50 6 200006 10 5 50 7 200007 10 5 50 8 200008 10 5 50 9 200009 10 5 50 10 200010 10 5 50 11 200011 10 5 50 12 200012 10 5 50 13 200101 10 5 50 14 200102 10 5 50 15 200103 10 5 50 16 200104 10 5 50 17 200105 10 5 50 18 200106 10 5 50 19 200107 10 5 50 20 200108 10 5 50 21 200109 10 5 50 22 200110 10 5 50 23 200111 10 5 50 24 200112 10 5 50 data have1; set have; date1 = put(date,6.); date2 = input(date1, yymmn6.); format date2 monyy7.; quarter = qtr(date2); year = year(date2); run; proc sort data = have1; by year quarter; run; ods trace on; proc means data = have1 sum; var quantity price totalprice; class year quarter; ods output summary=out1; run; ods trace off; data havefinal (drop = Nobs VName_quantity VName_price VName_totalprice); set out1; run; ods html; proc print data = havefinal noobs; run; ods html close; year quarter quantity_Sum price_Sum totalprice_Sum 2000 1 30 15 150 2000 2 30 15 150 2000 3 30 15 150 2000 4 30 15 150 2001 1 30 15 150 2001 2 30 15 150 2001 3 30 15 150 2001 4 30 15 150 If you have country variable then just add country before year in PROC SORT and PROC MEANS.

VX_Xc · ‎02-16-2012

Tools > New Library > tick "enable at start up"

VX_Xc · ‎02-16-2012

Thank you. Please correct me if I'm wrong regarding AIC.

VX_Xc · ‎02-16-2012

This is what I was looking for. sad predefined distributions are so limited. Guess I could use PROC FCMP to define distributions that are not predefined. OR... do you know any site that lists other distrtibution functions using PROC FCMP?

VX_Xc · ‎02-16-2012

Thank you for your help. I could try PRCO GENMOD... in DIST option do you know how many distributions are available? I disagree with you regarding the use of AIC. AIC is a holistic approach to comparing different models, it can do more than comparing various models that have different covariates (it is used to compare any parametric models as it uses likelihood function). AIC is used to test models that are not nested (but of course it can be used for nested models), for example if we have totally different models not only in covariates but also in methods used to fit the model we can compare which model is a better fit by comparing AICs. As distribution functions can differ in number of parameters to estimate and as AIC also takes this in to account (-2LL + 2p), AIC and other ICs, I believe, are the best way to compare parametric models. Please correct me if I'm wrong.

VX_Xc · ‎01-28-2012

Could anyone tell me where I could find a reference on how to automatically fit distribution function in SAS based on AIC or BIC (or Any Information Criterion). Thank you.

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How do I extract leading non zero digits?

Pairing two variable values.

Can SAS be hook up web service so that SAS performs real time computat...

Can SAS be hooked up to web server for the purposes of real time compu...

Proc Optmodel Help

Re: Proc Optmodel Help

Re: linear regression underestimation

why selection=stepwise is not one very good way to do regression?

How to create permanent libnames in my program

Re: from monthly dataset to quarterly

why selection=stepwise is not one very good way to do regression?

Create new variable based on two date variables matching

Re: Why? (simple INPUT option)

Re: from monthly dataset to quarterly

How do I extract leading non zero digits?

Pairing two variable values.

Can SAS be hook up web service so that SAS performs real time computat...

Can SAS be hooked up to web server for the purposes of real time compu...

Proc Optmodel Help

Re: Proc Optmodel Help

Re: linear regression underestimation

why selection=stepwise is not one very good way to do regression?

How to create permanent libnames in my program

Re: from monthly dataset to quarterly

How to create permanent libnames in my program

Re: Automatic distribution-fitting procedure.

Re: Automatic distribution-fitting procedure.

Re: Automatic distribution-fitting procedure.

Automatic distribution-fitting procedure.