Jan
23
comment What makes something a "Probability"?
@user692704 en.wikipedia.org/wiki/Probability_axioms
Jan
17
comment Remedy for failure to satisfy Proportional Hazards Assumption?
Look into time-dependent coefficients, for example here (but the amount of material you can find online is huge): tinyurl.com/h4qffy7
Jan
14
comment I am part of a “study team” that authored a paper. How do I list in in my CV?
Partially relevant? academia.stackexchange.com/questions/3260/…
Jan
3
comment Why does the t-test assume normality?
See here stats.stackexchange.com/questions/141314/…
Nov
13
comment How can we derive Woolf's method?
Also, this Woolf B. On estimating the relationship between blood group and disease. Human Genetics 1955; 19:251–253. and this Bagos P.G. On the covariance of two correlated log-odds ratios. Stat Med 2012; 31(14):1418–31 might be useful @yusuf
Nov
13
comment What incentives can a faculty member offer to a potential lab manager?
Very useful answer. As I'm considering to apply for one of those types of positions (as opposed to a postdoc) this was extremely helpful. +1.
Nov
12
comment How can we derive Woolf's method?
take a look at this technical report s3-us-west-1.amazonaws.com/hss-prod-storage.cloud.caltech.edu/…
Sep
21
comment What is the average number of references in a PhD thesis?
As always, PhD Comics has the answer to all your questions: phdcomics.com/comics/archive/phd091615s.gif
Aug
20
comment Interpretation of $\mathbf{y}^T(\mathbf{I}-\mathbf{H})\mathbf{y}$ in OLS
Thank you very much. Great explanation.
Aug
19
accepted Interpretation of $\mathbf{y}^T(\mathbf{I}-\mathbf{H})\mathbf{y}$ in OLS
Aug
19
asked Interpretation of $\mathbf{y}^T(\mathbf{I}-\mathbf{H})\mathbf{y}$ in OLS
Aug
5
comment Do you include papers that you contributed to but weren't cited as an author in on your CV?
Related: academia.stackexchange.com/questions/1112/…
Jul
3
comment What causes differences in estimates of 95%CI of the mean across subgroups in Stata?
What is causing such behavior is the choice of the degrees of freedom for the t distribution from which the quantiles necessary to the calculation of the Cis are derived. For example, in your first example 26.33333 - invttail(20, .025)*3.122499=19.819911, while in your second example 26.33333 - invttail(58, .025)*3.122499=20.082969
Jun
29
awarded Popular Question
Jun
21
comment How to do Cox regression if we have a variable which violates an assumption?
Do you mean that it violates the proportional hazards assumption? You can look into Cox models with time-dependent (or time-varying) coefficients. For example see here: Heinzl, H., & Kaider, A. (1997). Gaining more flexibility in Cox proportional hazards regression models with cubic spline functions. Computer methods and programs in biomedicine, 54(3), 201-208
Jun
17
comment Listing acknowledgments on CV
See academia.stackexchange.com/questions/1112/…
May
27
comment What is the right way of computing baseline hazard rate
Besides piecewise exponential models (Poisson) with splines to model the baseline hazard suggested by AdamO, an alternative is using Royston-Parmar models (flexible parametric survival models)
Apr
16
comment PH assumption: categorical variable (1 category does not interact with time)
Creating dummy variables beforehand is a possible way to go. In this example, the variable drug has 3 levels (2 dummy variables in the model), but I let only one of the 2 dummy variables (i.e. only one of the drugs, here) to interact with log(time): webuse cancer xi i.drug stcox i.drug, tvc(_Idrug_3) texp(log(_t)) - hope the syntax is clear
Apr
14
comment Is $R^2$ useful or dangerous?
@probabilityislogic Do you have a reference for the relation between $AIC$ and $R^2$?
Mar
25
comment Discrepancy between metafor and weighted lm() standard errors
The PDF manual for Stata's vwls command contains the answer to your question: stata.com/manuals13/rvwls.pdf See Section "Remarks and examples".
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