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Questions related from Igor Shuryak
I am using the grf R package (https://grf-labs.github.io/grf/reference/causal_forest.html) to obtain causal effect estimates for a continuous treatment variable. The package description says:...
16 January 2024 2,060 0 View
For example, suppose the data set is analyzed by random forest, and I make the partial dependence plot for predictor variable x. The same data set was also analyzed by a different model, and the...
13 May 2021 5,681 9 View
I am considering using causal random forests to detect/quantify potential causal effects of a variable of interest (e.g. radiation dose) on an outcome variable (e.g. some type of radiation-induced...
28 April 2021 8,788 2 View
I would be grateful for suggestions to solve the following problem. The task is to fit a mechanistically-motivated nonlinear mathematical model (4-6 parameters, depending on version of assumptions...
15 April 2020 2,430 12 View
I have data on numbers of taxa found in water samples from different locations (lakes) as the dependent variable, and many potential predictor variables (e.g. concentrations of various chemicals)....
12 April 2017 2,295 7 View
Specifically, the data set consists of a heterogeneous group of individuals which can be divided into many sub-groups. The random effects (e.g. intercepts and/or slopes) in a mixed COX model could...
27 April 2016 2,290 1 View
The task involves predicting a binary outcome in a small data set (sample sizes of 20-70) using many (>100) variables as potential predictors. The main problem is that the number of predictors...
02 November 2015 4,584 10 View
Soil samples were taken from two locations which differ by the values of several variables (x1, x2, etc). There were N1 samples from location 1 and N2 samples from location 2. The total number of...
08 May 2015 5,995 11 View
The situation is as follows: An experiment measured the concentration of a certain chemical in cells at various times after exposure. The results were normalized by the concentration at time zero,...
03 October 2014 8,327 10 View
Suppose a mathematical model consisting of a system of differential equations is constructed to describe some biological phenomena. Analytic solutions are not available - only numerical ones. Are...
01 April 2014 3,498 15 View
For example, suppose a certain method was chosen for power/sample size calculation for a future experiment, with the intent to use the same method to analyze the experimental data. But the...
06 January 2014 2,463 18 View
Among the many available methods, which are the most efficient (i.e. require the smallest sample size for defined alpha and beta) and relatively straightforward to implement?
20 December 2013 869 9 View
Suppose there are several treatment groups. Within each group there are exponentially distributed data, i.e. the number of counts is proportional to exp[-A*x^B], where A and B are parameters. What...
01 October 2013 4,916 55 View
Suppose a non-linear smooth function is fitted to some data (e.g. means and standard errors for cell survival after various radiation doses). What are some useful ways to assess goodness of fit...
06 September 2013 9,619 45 View
The issue is how to induce U. maydis cells to attach to the bottom of a culture dish, which is composed of a mylar film. Thanks in advance!
27 August 2013 4,927 0 View
I used PRCC in one paper (A model of interactions between radiation-induced oxidative stress, protein and DNA damage in Deinococcus radiodurans, available on my page) because reviewers requested...
22 August 2013 968 4 View
I wonder about this because for such small data sets it is not always clear whether the data are normally distributed, so perhaps results (p values) from both parametric and nonparametric tests...
01 August 2013 3,889 73 View
Suppose nonparametric bootstrapping is used to estimate the sensitivity of the fitted model to parameter values. Does this technique work reasonably well for small data sets (e.g.
31 July 2013 2,171 7 View
There are several commonly used normality tests. I wonder what do you suggest is optimal for small data sets?
15 July 2013 347 63 View
For example, suppose a nonlinear model is fitted to a data set. It is possible to map out a region in the parameter space around the best-fit point, within which the residual sum of squares...
11 July 2013 2,074 35 View
In other words, can alpha/beta ratios for the same cancer type depend on dose per fraction?
02 July 2013 9,206 5 View
For example, do C. neoformans cells secrete signals which stimulate other C. neoformans cells to proliferate or not to priliferate?
02 July 2013 3,552 0 View
For different radiotherapy techniques, the ratio of isocenter/peripheral doses differs substantially. Is anything known about which region - center or periphery - is most relevant for tumor killing?
27 June 2013 5,842 19 View
For example, comparing stereotactic techniques with large doses per fraction to standard fractionation?
24 June 2013 8,179 7 View
For example, assuming a sufficiently long inter-fraction repair period, does increasing the dose per fraction reduce the relative gain in survival?
20 June 2013 4,545 1 View
For example, what about effects of alpha-emitting radionuclides?
12 June 2013 2,714 4 View
