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Free statistics help forum. Discuss statistical research, data analysis, statistics homework questions, R, SAS, Stata, SPSS, and more.enFri, 28 Nov 2014 02:42:07 GMTvBulletin60http://www.talkstats.com/images/misc/rss.pngStatistics Help @ Talk Stats Forum
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What is the “pdm” stat in the “rms” R package?
http://www.talkstats.com/showthread.php/58635-What-is-the-“pdm”-stat-in-the-“rms”-R-package?goto=newpost
Fri, 28 Nov 2014 00:17:16 GMTI am new to the world of Regression in statistics and I have been doing a research in which I am building an ordinal logistic regression model (ORM)....I am new to the world of Regression in statistics and I have been doing a research in which I am building an ordinal logistic regression model (ORM). In order to fit my ORM model, I am using the 'orm' function of the 'rms' package from R (http://cran.r-project.org/web/packages/rms/rms.pdf).

Now I am trying to assess the goodness of fit of my model. By reading the R documentation, I can see the following statement in the 'stat' property of the 'orm' object (pg.98):

"(...)Nagelkerke R2 index, the g-index, gr (the g-index on the odds ratio scale), and pdm (the mean absolute difference between 0.5 and the predicted probability that Y >= the marginal median)(...)."

I don't have enough background to understand the short description of the pdm measure. But when I try to do more research on this measure, I am not able to find related material (e.g. I've been finding "prescription drug misuse"). In summary, my question is:

Would you know if the 'pdm' measure has some synonym which is more widely used? Or can you provide some references where I can study the pdm metric?
]]>Regression Analysisdanielalencarhttp://www.talkstats.com/showthread.php/58635-What-is-the-“pdm”-stat-in-the-“rms”-R-packageAnalyzing a Line Chart
http://www.talkstats.com/showthread.php/58634-Analyzing-a-Line-Chart?goto=newpost
Thu, 27 Nov 2014 23:29:16 GMTI have a line chart with number of people on the y axis and weeks on the x axis. I was wondering if someone knew how to analyze or determine the...I have a line chart with number of people on the y axis and weeks on the x axis. I was wondering if someone knew how to analyze or determine the percent change over the entire period of time of the graph? Any suggestions would be helpful. Thank you.
]]>Statisticscg21http://www.talkstats.com/showthread.php/58634-Analyzing-a-Line-ChartDefinition of z-score...
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Thu, 27 Nov 2014 23:27:27 GMTI need help with this question:
Define the standardized value or z-score corresponding to a given observation y in a normal distribution. Explain...I need help with this question:

Define the standardized value or z-score corresponding to a given observation y in a normal distribution. Explain all the symbols you use.
]]>Statisticsveganrawhttp://www.talkstats.com/showthread.php/58633-Definition-of-z-score...