Questions tagged [regression]
Techniques for analyzing the relationship between one (or more) "dependent" variables and "independent" variables.
30,803 questions
3
votes
1
answer
24
views
How to handle calendar year as a continuous predictor with a mismatched train/test time horizon?
I am using Ordinal Semiparametric Regression (Frank Harrell's rms package) to model overall survival in patients with brain tumor.
My training data is from the SEER database (covering years 2004 to ...
- 171
2
votes
1
answer
26
views
Best method to determine sub-sensor error
I have a system measuring several outputs by sub-sensors and the total input to the sub-sensors is measured from a main sensor.
The above chart shows the error between the sum of sub-sensor readings ...
- 21
6
votes
2
answers
208
views
Singularity Problem with gls that isn't present in lm
I'm performing an IPD meta-analysis, and need to fit my models with study-specific variances (which is why I need to fit with nlme::gls instead of ...
- 181
7
votes
2
answers
275
views
How to decide if an interaction exists: graphically/interaction terms/contrasts of slopes
I have fit interaction models of the form: phenotype ~ genotype * environment, based on theory.
I am assigning environment (GFR, in this case) as the moderator.
I have three scenarios:
A: Non-parallel ...
- 191
7
votes
2
answers
261
views
Multiple regression when some predictors are identical across groups
I am working on a multiple regression model examining the effects of several predictors on morphological traits to make interspecific comparisons across many species:
Length ~ Height + Average Weight +...
- 71
0
votes
0
answers
26
views
Using total least squares (TLS), finding right standard deviation if x,y scales change after fit
I am looking to fit experimental data to a line that predicts whether a circular pad will slip. This is done considering the shear force and the moment applied on the pad. I would also like to get a ...
user509159
6
votes
2
answers
252
views
Do Spline Terms Affect the Interpretation of Linear Terms in Logistic Regression?
In a multivariable logistic regression model, some continuous predictors are modeled using spline transformations to allow for nonlinear effects, while other continuous predictors are entered as ...
1
vote
0
answers
41
views
How to interpret the two equations of a linear regression?
I have $n$ data points $(x_i, y_i)$ and I am looking for two coefficients $(a, b)$ such that $$\forall i,\quad y_i \approx a x_i + b.$$
I define the mean square error function $$L(a, b) = \sum_i (y_i -...
- 499
5
votes
1
answer
132
views
How to incorporate survey weights in multilevel regression with country-level grouping?
I am seeking guidance on how to properly account for survey weights in a nested (multilevel) regression analysis.
Context: I have categorized countries into three groups based on country-level ...
- 121
6
votes
1
answer
137
views
Do these different expressions for $R^2$ compute different things? If so, which one is appropriate?
I've encountered two different formulae to compute $R^2$ (explained variance, coefficient of multiple correlation, or coefficient of determination).
The first,
$$R^2 = b_{yx}^T R^{-1}_{xx} b_{yx},$$
I'...
- 446
3
votes
1
answer
140
views
Why is the procedure in the paper that uses cross-validation instead of hypothesis test on reduced rank regression feasible?
In one computational biology paper, the authors was performing a reduced rank regression of the form
$$ \vec y= B\vec x+ \vec \epsilon $$
where $\vec y$ is the response variable, $\vec x$ is the ...
- 337
3
votes
3
answers
244
views
Choosing splines terms for continuous predictors
I’m fitting a regression model with several continuous predictors, and I suspect some of them may have nonlinear effects (yeah, yeah, Box-Tidwell may answer that).
Is it reasonable to use AIC to ...
1
vote
1
answer
86
views
Is the Joint F test overly optimistic?
I have multiple groups. Each group has a response variable and 7 predictors. I fit a separate regression model to each group. I calculate the percent of predictors in each group that have ...
- 169
1
vote
2
answers
74
views
Best regression approach for linking many correlated physico‑chemical properties to degradation rates
I have measured the concentration of 76 pesticides (acttive ingredients) at three time points during freeze‑drying (6 h, 24 h, 76 h), with three replicates per time point. For each pesticide, I also ...
- 91
0
votes
0
answers
51
views
Regression model on discounts
I need to build a statistical model to analyse discounts. For every sale, I know both the net price and the list price. Let the discount be:
$$discount := \frac{net \; price}{list \; price}-1$$
For ...
- 2,201