02-25-2023
gcjfernandez
SAS Employee
Member since
09-18-2013
- 151 Posts
- 0 Likes Given
- 40 Solutions
- 45 Likes Received
About
George Fernandez, former professor of applied statistics, and the Director for the University of Nevada- Reno Center for Research Design and Analysis currently serves as Senior Analytical Consultant, SAS Education. He has more than 23 years of experience in teaching courses such as design and analysis of experiments, linear and non-linear regression, multivariate statistical methods and SAS programming. He has over 25 years experience in many statistical and graphical SAS modules. He has won best paper and poster presentation awards at the regional and international conferences. He has presented several invited full-day workshops on "Applications of user-friendly statistical methods in Data mining: American Statistical Association Joint meeting in Atlanta (2001), Western SAS users Conference in Arizona (2000), in San Diego (2002),and San Jose (2005), 56th Deming's conference, Atlantic City (2003), Key-note Speaker and workshop presenter, 16th Conference on Applied Statistics, Kansas State University. He has also organized 7th Western Users of SAS conference (WUSS) at Los Angeles in 1999 and served as the section chair, SUGI31 and SGF2007-2009. His book on "Data mining using SAS applications" (CRC press / Chapman Hall) contains many user-friendly SAS macro-applications.
Specialties: Training Consultant in SAS Forecast Server/Studio, SAS Enterprise Miner, SAS survey probability design course, SAS/STATS and SAS/ETS, programming, Data Mining, SAS Visual text analytics,and Visual forecasting.
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Latest posts by gcjfernandez
Subject Views Posted 1126 08-04-2022 12:11 PM 492 07-22-2022 03:30 PM 462 07-22-2022 03:17 PM 5412 04-25-2022 01:47 PM 984 03-03-2022 01:56 AM 1019 03-02-2022 03:04 PM 488 03-02-2022 01:59 AM 1264 10-18-2021 06:29 AM 1282 10-18-2021 02:44 AM 1299 10-18-2021 01:35 AM -
Activity Feed for gcjfernandez
- Got a Like for Re: Intuitive Way to Interpret Intercept Value of Shapley Values Output. 09-03-2023 06:36 PM
- Posted Getting Started with SAS® Visual Text Analytics Q&A, Slides, and On-Demand Recording on Ask the Expert. 08-04-2022 12:11 PM
- Got a Like for Webinar on July 28th, 11 AM – Noon ET entitled Getting Started with SAS® Visual Text Analytics. 07-22-2022 03:32 PM
- Posted Webinar on July 28th, 11 AM – Noon ET entitled Getting Started with SAS® Visual Text Analytics on SAS Visual Analytics. 07-22-2022 03:30 PM
- Posted Webinar on July 28th, 11 AM – Noon ET entitled Getting Started with SAS® Visual Text Analytics on SAS Data Science. 07-22-2022 03:17 PM
- Posted Re: Intuitive Way to Interpret Intercept Value of Shapley Values Output on SAS Data Science. 04-25-2022 01:47 PM
- Posted Re: New mean of variable after adjusting for covariate for total population on Statistical Procedures. 03-03-2022 01:56 AM
- Posted Re: New mean of variable after adjusting for covariate for total population on Statistical Procedures. 03-02-2022 03:04 PM
- Posted Re: Survey Select cascading stratified random sampling on Statistical Procedures. 03-02-2022 01:59 AM
- Got a Like for Re: NLP LITI Rules. 01-31-2022 05:20 PM
- Posted Re: SAS EM: decision tree on SAS Data Science. 10-18-2021 06:29 AM
- Posted Re: SAS EM: decision tree on SAS Data Science. 10-18-2021 02:44 AM
- Posted Re: SAS EM: decision tree on SAS Data Science. 10-18-2021 01:35 AM
- Posted Re: Modify a variable in SAS Miner on Statistical Procedures. 10-18-2021 01:17 AM
- Posted Improved ways to classify over-weight and obesity: Welcome Body Fat Index (BFI) on SAS Communities Library. 10-17-2021 02:04 AM
- Posted Re: Decision tree splitting rule in SAS EM on SAS Data Science. 10-14-2021 02:18 AM
- Posted Re: Decision tree splitting rule in SAS EM on SAS Data Science. 10-13-2021 06:36 PM
- Posted Re: In SAS EM, how can I know which one is the base level for nominal variable? on SAS Data Science. 10-07-2021 01:47 AM
- Posted Re: In SAS EM, how can I know which one is the base level for nominal variable? on SAS Data Science. 10-06-2021 05:15 PM
- Posted Re: In SAS EM, how can I know which one is the base level for nominal variable? on SAS Data Science. 10-06-2021 12:16 AM
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My Liked Posts
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My Library Contributions
Subject Likes Author Latest Post 0 0 1 0 0
03-06-2021
01:38 PM
If you used SAS sentiment analysis studio before you can get a binary file with SAM extension. You can use this SAM file in SAS VTA when using the sentiment node.
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03-06-2021
01:19 PM
You could try the DROP variable node from the MODIFY Tab in SAS Enterprise minor to drop this txt variable before connecting the Topics node
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03-06-2021
01:12 PM
You can create EM projects using the Chapter SAS data files and the XML files to create the process flow diagrams described in the chapters. To use the SAS programs files, you need to run in the SAS code node. To create a new diagram, right click the diagram and you will see an option to use an XML file from a folder.
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03-06-2021
12:48 PM
Please use the SAS code provided in this link to create SAS data for a 2 factor factorial experiment with blocks: https://documentation.sas.com/?cdcId=pgmsascdc&cdcVersion=9.4_3.3&docsetId=statug&docsetTarget=statug_code_glmex3.htm&locale=en
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12-17-2020
05:59 PM
1 Like
Watch this Ask the Expert session to learn how to use SAS survey tools to design and analyze big survey data scientifically.
Watch the webinar
Join George Fernandez as he discusses why survey analytics differs from other standard statistical procedures. He will cover data exploration, description, model building and interpretation. Watch this webinar to learn:
Why standard statistical procedures are inappropriate for analyzing probability surveys.
How to use advanced features included in the SAS survey procedures.
How to explore, summarize, fit the model and interpret results using SAS survey procs.
How to use the popular NHANES survey data in a live demo of the advanced features of SAS survey procs.
The questions from the Q&A segment held at the end of the webinar are listed below and the slides from the webinar are attached.
Do you know if SAS plans to add a new survey procedure to fit Poisson regression?
I don’t think SAS is going to add a new Survey procedure to handle Poisson regression directly, but please follow the directions provided in these links:
https://support.sas.com/rnd/app/stat/examples/SurveyPoisson/surveypoisson.htm
https://support.sas.com/rnd/app/stat/examples/SurveyPoisson/sas.html
If I want to do analysis on a sub-population, such as ages 18-64 and employed at time of interview, is it okay to use a where statement or is the only correct option to use domain?
You should always use domain statement for sub-population analysis unless you modified the target population.
Why does PROC SURVEYMEANS not report Standard deviations?
PROC SURVEYMEANS computes the NOBS, MEAN, STDERR, and CLM statistics by default, but you can request standard deviation by adding STD as an option. Please check the documentation for additional keywords.
Does SAS have the option to specify the type of adjustment (ie TUKEY) when comparing the domain means?
Unfortunately, Only Bonferroni adjustment is available in SURVEYMEANS Domain statement for mean comparison.
Can PROC SURVEYFREQ do a Cochran-Armitage trend test?
Unfortunately, Cochran-Armitage trend test is not included with PROC SURVEYFREQ at this time.
How do you compare the domain means (get a p.val) when using ratio estimation of PROC SURVEYMEANS? E.g., If we know one ratio variable's mean and sex in women and men (sex as a domain), how can we get the p.val between them?
Comparing Ratio means is implemented using the SMSUB SAS macro. Please contact SAS Technical Support for more information about using this SAS macro using SAS IML.
How would you approach testing for between group differences for categorical variables and a 3 x 3 table?
You could try to fit a Generalized logit model using PROC SURVEYLOGISTIC after collapsing 3 x 3 two-way combinations to one-way with 9 levels and using LSMEANS or LSMESTIMATE statements in PROC SURVEYLOGISTIC.
Could PROC MIXED be used to analyze survey data with design and stratification weights?
PROC MIXED is not supported for Survey analysis. But PROC GLIMMIX is supported. Please watch https://www.youtube.com/watch?v=VE_HM8JcMZM
And refer to this document: https://support.sas.com/resources/papers/proceedings14/SAS026-2014.pdf
Will survey procedure be implemented specifically for the propensity score matching?
Not within Survey procs. Please refer the new SAS STAT procedure PSMATCH documentation at https://support.sas.com/documentation/onlinedoc/stat/142/psmatch.pdf for propensity score matching in general.
Can you please explain more under condition(s) to use the different variance estimation methods, e.g. Taylor series, jackknife, etc.
Tyler series method is the default method in all survey procs. You need to always include survey design details with Tyler method. If you use the replication-based methods (BRR, JK etc.), after generating replicate weights, you can omit the survey design (Cluster, strata) details. This is the most significant advantage with these replication-based weights. But the computation time may be significantly higher with big data.
Do we need SUDAAN if we have the SAS SURVEY Procedures? Can the SURVEY procedures do everything that SUDAAN can do?
SAS SURVEY procedures can do almost everything SUDAAN can do. If you want to check on something, please just search sas.com to check for documentation on the item in question.
Can SAS calculate temporal trend for survey data?
Not directly within the SAS Survey procs. You can try Proc GLIMMIX with time correlated covariance structure.
Can you not use where/by statements with the BRR variance method?
Where or By statement is not recommended with Designed surveys. Try to use domain statement for subpopulation analysis with BRR or JK methods.
Will PROC SURVEYIMPUTE create multiple imputed complete data and export for later analyses?
Multiple imputed data sets are only needed when used with PROC MI/MINANALYSE procs. SURVEYIMPUTE generates replication-based weights and these datasets can be saved and used subsequently with any other SAS survey analysis procedures.
Why is it so hard to estimate standard error using survey data?
Because when survey data are collected based on specific survey designs (not just from random sample) and estimation and inferences are needed for finite population we must use specialized methods to estimate variances and covariances. That is why we use special survey procs within SAS/STAT to estimate the standard errors.
When using PROC SURVEYIMPUTE, do replication weights also need to be used?
Yes, you need to use replication weights because SAS is using replication-based variance estimation methods when imputing missing values.
Do you need to set up the number of imputed data that you want to obtain with PROC SURVEYIMPUTE?
Number of imputed data sets is only needed when used with PROC MI and PROC MINANALYSE.
Could you speak about the different options for confidence intervals? My colleagues were recently discussing using type=logit in PROC SURVEYFREQ.
You can specify TYPE=Logit with PROC SURVEYFREQ. This specifies the type of confidence limits to compute for proportions. If you do not specify the TYPE= cl-option, PROC SURVEYFREQ computes Wald confidence limits (TYPE=WALD) by default.
You can specify one of the following confidence limit types:
LOGIT = requests logit confidence limits for proportions. If you specify the CL(TYPE=LOGIT) option, PROC SURVEYFREQ computes logit confidence limits for proportions. For more information, see Agresti (2013) and Korn and Graubard (1998).
I want to learn SAS. What is the price for it?
You can learn more about SAS on our website. We also have some free training available right now that I encourage you to explore.
Is SAS planning to add more diagnostic such as goodness of fit test in SURVEYLOGISTIC?
Please contact SAS Technical Support for more information about the SURVEYLOGISTIC procedure.
Recommended Resources
Wait Wait, Don't Tell Me… You're Using the Wrong Proc!
SAS/STAT® 14.3 User’s Guide Introduction to Survey Sampling and Analysis Procedures
The Latest and Greatest Capabilities of the SURVEY Procedures
Want more tips? Be sure to subscribe to the Ask the Expert board to receive follow up Q&A, slides and recordings from other SAS Ask the Expert webinars.
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11-30-2020
12:39 AM
Hi SAS Procedures Community,
I’m presenting a live “Ask the Expert” webinar on December 15 th , 1 PM – 2 PM ET entitled What Are Best Practices for Using SAS Survey Procedures? Join me for this webinar to learn how to use SAS survey tools to design and analyze big survey data scientifically. I’ll answer your questions during the Q&A session at the end of the webinar.
You will learn:
Why standard statistical procedures are inappropriate for analyzing probability surveys.
How to use advanced features included in the SAS survey procedures.
How to explore, summarize, fit the model and interpret results using SAS survey procs.
How to assess the impact of improved obesity-overweight classification based on the new Body Fat Index using the popular NHANES survey data.
... View more
11-30-2020
12:33 AM
Hi SAS Statistical Procedures Community ,
I’m presenting a live “Ask the Expert” webinar on December 15 th , 1 PM – 2 PM ET entitled What Are Best Practices for Using SAS Survey Procedures? Join me for this webinar to learn how to use SAS survey tools to design and analyze big survey data scientifically. I’ll answer your questions during the Q&A session at the end of the webinar.
You will learn:
Why standard statistical procedures are inappropriate for analyzing probability surveys.
How to use advanced features included in the SAS survey procedures.
How to explore, summarize, fit the model and interpret results using SAS survey procs.
How to assess the impact of improved obesity-overweight classification based on the new Body Fat Index using the popular NHANES survey data.
... View more
10-07-2020
12:49 PM
This is what I ended up with. I think it is correct, but now SAS is saying there is insufficient memory to run this, even after I adjusted MEMSIZE. But anyways, maybe this is helpful: proc sort data=PATH_DATA; by ID WAVE; run; proc glimmix data=PATH_DATA; class GENDER2 RACE2 HISPANIC2 AGE2 ALCOHOL CIG DIABETE EDUC1 EMPLOY1 DUAL VARPSU VARSTRAT INCOME MARITAL1 BMI INSURANCE1 REGION1; model STROKE = GENDER2 RACE2 HISPANIC2 WAVE AGE2 ALCOHOL CIG DIABETE EDUC1 EMPLOY1 DUAL INCOME MARITAL1 BMI INSURANCE1 REGION1/ link=logit solution oddsratio; random WAVE intercept / subject=ID; random VARPSU(VARSTRAT); weight WEIGHT; run;
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10-05-2020
10:42 AM
1 Like
I am attaching the screenshot from SAS Enterprise miner Reference documentation 14.3 where you can find the official computation description.
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10-03-2020
02:59 PM
1 Like
Please provide the following details: What is the version of SAS VTA? Which course data you are referring?
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10-03-2020
02:51 PM
I think the problem is in the By statement. Provide more details about the by statement. What happens if you run the code without the By statement?
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10-02-2020
01:48 AM
When decision tree modeling with chi-square (Nominal target) or F-test (Interval target) are used, to control the comparison wise error rates associated with comparing many split points Bonferroni and Kass adjustments are made to the log woth statistics. This adjustments minimizes over fitting. Please read this paper: https://www.aaai.org/Papers/KDD/1997/KDD97-038.pdf
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07-17-2020
04:53 PM
Thank you so much. This worked and was shorter. I solved the problem by creating a dataset containing smoke 1 vs 0, and then creating 4 dataset from that have the parameter estimates of each level of my composite variable. I then used proc mianalyze on each of the 4 datasets and each dataset gave me the OR. Longer but it did it. Thanks so much!
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06-06-2020
09:57 PM
1 Like
Class statement in Proc Autoreg is experimental now. However you could fit models with categorical variables just like GLM using the class statement. You could also try any potential interactions with the class statement. Make sure use appropriate AR terms to accomadate autocorrelation.
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09-12-2017
06:00 AM
Thank you for your help
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