All Questions
211,781
questions
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17
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Are these two estimated regression coefficient asymptotically equivalent? If not, which one is more efficient?
Suppose I have $Y=\beta_1X_1+\beta_2X_1X_2+g(X_2)+u$, where $E(u|X_1,X_2)=0$ and $S=g(X_2)+e$ with $E(e|X_2)=0$. I have a random sample $\{Y_i,X_{1i},X_{2i},S_i\}_{i=1}^n$. Suppose I first use a ...
- 2,526
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votes
1
answer
43
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Can logistic regression predictor variables be nominal?
Can logistic regression predictor variables be nominal (like the charlson comorbidity index which ranges from 0-6)?
1
vote
1
answer
44
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Can I estimate the mean of a dataset if I have its standard deviation and a portion of the full data that is higher than some threshold?
I have a partial set of measurement data that is limited due to my tool's sensitivity. I know that the data is approximately normally distributed and I have a standard deviation from another data set ...
- 11
1
vote
1
answer
41
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Sample Size Calculation for Gene and Protein Biomarker Study
The PIs are looking for biomarkers in pre and post-trauma individuals. I need to calculate a sample size for a microarray study of 10 genes and the top 5 up- and down-regulated proteins and ...
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0
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20
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compare the outcome of logistic regression (predictive probabilities) before and after an event
To train a glm model, I'm using using clinical data (~10 features) of a large cohort of patients and healthy subjects. I'm using a smaller test group (around 20 people) and predict their outcome (...
- 101
0
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1
answer
25
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AR(n) process error variance in R
I was wondering where does the "sigma^2 estimated as 12.2" in the following example came from. I tried to compute by myself the variance of the residuals, however it seems I probably forgot ...
- 1
0
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0
answers
6
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Alternatives to partial mantel test for removing spatial autocorrelation in R?
I have a presence/absence distance matrix based on eDNA sampling for certain species at ~30 sites. I would like to see if the volume of water filtered influences species detection, accounting for the ...
- 1
0
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0
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5
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Multi-level meta: do I include a measure of precision in subgroup analysis model?
In a meta-regression model, a precision measure (SE or SE^2) is often included in the model along with covariates. Is the same true for subgroup analysis in a multi-level analysis wherein moderators ...
- 1
0
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0
answers
10
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Significance test to compare groups when a variable has multiple occurences per case
I'm finishing a manuscript, but have one nagging problem which I'm unable to find an answer.
Study has two groups which receive different procedure for a disease. After the procedure, one patient may ...
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answers
10
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Modeling a chargeback rate as a function of an approval rate
I am working on a problem where I would like to estimate chargeback rates for online goods orders as a function of the proportion of orders that are approved (approval rate).
The approval rate is a ...
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0
answers
5
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Is it appropriate to conduct a Kruskal-Wallis test with the mean of a 3 item construct measured on a 7-point Likert scale as independent variable?
I am working on my master's thesis and conducted two studies. The first study utilizes 3 groups. The problem is, that the group sizes are very small (n1 = 13, n2 = 14, n3 = 14). I want to test if ...
- 1
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0
answers
12
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Understanding parameters interaction contrasts in model averaging
I am struggling to understand how parameter interaction contrasts play into model averaging. As I am new to Stack Exchange, I apologize if my question is in the wrong place or incorrectly asked. I ...
- 1
1
vote
1
answer
18
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Significance test of an increase in adjusted R-squared between two models
I found two papers that provide their results showing the significance of an increase in adjusted R-squared between two models statistically, with p-values, to show the improvement after adding a few ...
- 143
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0
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23
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Does Maxwell–Boltzmann distribution belong to exponential family? [closed]
PDF - $\sqrt{\frac{2}{\pi}} \, \frac{x^2}{a^3} \, \exp\left(\frac{-x^2}{2a^2} \right)$
If yes - provide an estimator and parametric function ($T(X)$ and $\tau(a)$)
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vote
1
answer
40
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Summary from lme() output returning estimate value of 0?
I'm trying to run a linear mixed effects model using the nlme package using the lme() function with the txhousing data from the <...
1
vote
0
answers
25
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Applying a non-linear model to assess the difference between variables [duplicate]
I have already asked a similar question on this site (Correlating two variables / convergence); however, I feel like the way I wrote the previous one made it a bit too ambiguous, and on top of that, ...
- 31
1
vote
1
answer
46
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Matching order based on grouping variable
I want to match in a certain order.
I am aware of the argument order, available in package {MatchIt} - but this refers to the ...
- 97
0
votes
0
answers
11
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Reliability and repeatability [closed]
Which is the difference between reliability and repeatability and which test can use available in Jamovi?
- 11
0
votes
2
answers
44
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Regarding samples gotten from MCMC
In one article explaining MCMC, I once read the following statement.
The idea of sampling methods is the following. Let’s assume first
that we have a way (MCMC) to draw samples from a probability
...
- 3,017
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0
answers
10
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Why the F test is NA in R package Fect?
I am a new learner of Fect package in R, see https://yiqingxu.org/packages/fect/fect.html.
I try to use method to do counterfactual analysis of my DiD. I use unbalanced panel data, and the Matrix ...
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0
answers
14
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What embeddings are used in decoder-only models like GPT?
Decoder-only models do not use an encoder. Hence, they do not get the embedding from it.
I went through this nice description of a decoder-only transformer -based model
I do understand the training ...
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4
votes
0
answers
55
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Sum of Independent Laplacian Variables
I have $N$ Independent Random variables Laplacian distributions with $\mu=0$ and positive $b=\sigma^2/2$. I also have dominant random variable $(X_s)$ with Laplacian distribution with $\mu=0$ and $b=\...
- 41
1
vote
1
answer
28
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Sample size calculation for the rate of infections between two groups
I am in the progress of calculating the sample size for a treated/untreated group comparison.
The data provided is a mean infection rate (mean/100 years) of a literature recherche.
Assuming the ...
- 21
2
votes
1
answer
76
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Bayesian stats and multiple tests
Are Bayesian models subject to the same problems as frequentist ones, where we cannot run a bunch of different models due to Type I error? For example, let's say I have a large data frame on airplanes,...
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0
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8
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Calculate when a time series will reach s specific value
I have a time series at day level granularity:
Date. Value
2023-10-01 78945
2023-10-02 78990
2023-10-03 79005
2023-10-04 78999
...
While there are some ...
- 101
0
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0
answers
27
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Calculate propensity scores using coefficients
I want to calculate propensity scores using the coefficients of a logistic model that was calculated using a random sample of this data:
...
- 97
1
vote
0
answers
21
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median imputation or case deletion for small samples
I have a dilemma. I have a data set of different proteins from 4 groups of animals characterized by two factors: age (3 or 12 months) and presence of a certain gene (KO or WT). For each combination of ...
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0
votes
1
answer
45
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multicollinearity and categorical variables
When performing regression with categorical variables, in order to avoid multicollinearity, it is necessary to drop one level. This is clear in fact:
Let's assume I have a binary categorical variable (...
1
vote
1
answer
35
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Does the likelihood of getting a certain person in secret santa decrease if you were going first versus going last, and how much?
Feeling a bit stupid but here goes:
There are 6 people in this secret Santa thing, one of them is person X and another is person Y. All the names are put into a hat and each person comes up to take a ...
1
vote
1
answer
19
views
Complete case analysis, multiple imputation, or instrumental variable analysis?
I ran a small study where all participants attended a psychological intervention, and completed measures at pre, post, and follow-up. Approx. 40 participants took part, of which approx. 5 did not ...
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0
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9
views
How can you constrain the intercept of a glmnet model to be positive?
If I use the lower.limits = 0 argument, it doesn't apply to the intercept for some reason. I can't find any documentation as to why or how to do it. Any ideas? ...
- 1,163
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0
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21
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How to calculate relative risk from GAM model in mgcv package? [closed]
I have daily air pollution parameters PM10, PM2.5 CO, NO2, SO2, and O3. I also have daily hospital admission numbers. Taking into account the effect of weekends and holidays, I would like to use ...
5
votes
2
answers
1k
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Can I use p-values without hypothesis?
I have been working on my Master's Thesis which included a survey and its results have been put through various tests. The unusual thing about my Thesis is that I have no hypotheses at all, making it ...
- 61
1
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0
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14
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Mixed effects model in R with subsampling in replicates
I am working on a mixed effects model in r where I have 2 treatments, 5 replications and subsampling with each site. I dont have access to the raw subsampling data though, I just have the mean effect ...
0
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0
answers
15
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1
vote
1
answer
28
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Should I use a mean-based measure of skewness or a median-based measure of skewness, when the distribution has a very long tail?
I am aware that measures of skewness based on the mean are affected by outliers, and just one outlier can significantly shift the mean. However, in case of a distribution with a very long tail, should ...
- 198
1
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0
answers
11
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Why is the concept of RKHS useful in kernel ridge regression?
The way I have seen kernel ridge regression introduced is as follows. Given data $(X,Y)$ you want to fit a function $f$ from a RKHS $\mathcal{H}$ to minimise some empirical loss $\sum_i L(f(x_i), y_i)$...
- 121
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0
answers
43
views
How can Bootstrapping explain the uncertainty of a statistic?
I have been reading about bootstrapping, and sampling distributions, and find it odd that people use these techniques to describe uncertainty.
As I understand it, the sampling distribution shows ...
- 461
0
votes
1
answer
29
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Confidence intrervals of precision and recall with unmbalanced data
Fictionalised example: There are two models in place to predict a rare form of cancer (1 in 80.000 or 0,001% occurrence). To evaluate the performance of these models, we calculate the precision (and ...
- 1
1
vote
2
answers
20
views
Interpretation dummy variables Cox PH model
I'm curious about interpreting the coefficients of dummy variables within a Cox Proportional Hazards (PH) model. Consider a scenario where I have a sample comprising both male and female patients, and ...
- 225
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0
answers
18
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Can I add a variable to a complex sample, and run a regression?
In a survey, a complex sample was collected, and the sample was designed to provide estimates at national level. In other words, individuals from one state were more likely to be sampled due to ...
- 349
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0
answers
15
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Dynamic Fixed Effect model [closed]
I am trying to test the hypothesis of economic convergence in European countries. I have found that a consistent estimator is Bias corrected LSDV (see, Kiviet (1995)). I've seen that there is a ...
0
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0
answers
7
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Can you explain the logic behind degrees of freedom for interaction effect in multi-factorial ANOVA?
I am currently trying to build intuition for two-factor ANOVA by doing some simulation in Python, and some things are hard for me to parse.
I have an ANOVA with 4 levels of one factor and 3 levels of ...
- 191
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0
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6
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What design would my research be if it has 1 iv with 3 levels and 1 dv?
I’m currently writing a research proposal and need to include my research design but I’m struggling to decide which one it would be.
My Iv is temperament with 3 different levels
1- behavioural ...
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0
answers
47
views
Density of sum of two random variables
Let$(X,Y)$ be an RV of the continous type with PDF $f(x,y)$.Let
$Z=X+Y$,then the Convolution of probability distributions told us the PDF of $Z$ is $f_{Z}(z)=\int_{-\infty}^{\infty}f(x,z-x)dx$.
If we ...
0
votes
1
answer
15
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Mediation analysis - Hayes Process plugin
I have a model to test 4 hypothesis (all data was collected on a 5-point likert scale through surveys):
Ability (IV) has a positive relationship with PO fit (M)
PO fit (M) has a negative ...
- 141
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0
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37
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What model could be the best for this problem?
I would like to know which model could be the best for the problem i have:
I have data at baseline, at 3 months Follow-up, and data until 2 years of follow up.
I have classified individuals as if they ...
- 23
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0
answers
17
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To create a vector from a vector in R software [closed]
I am new to R language.
Suppose I have a vector v<-c(1,6,7,4,6,9,20,15.....)
I want to create another vector c from this vector whose elements are suppose for example:-1st,4th,7th,10th,13th and so ...
2
votes
1
answer
46
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Interpreting intercept with centered predictors in logistic mixed model
I am running a logistic mixed model in lme4. The model is as follows
...
- 129
2
votes
1
answer
106
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Forecasting based on revenue and advertisement
How to forecast revenue based on previous revenue and advertisement budget?
This is how the data looks like, see full data on google sheet.
From the little that I know, Excel offers forecasting based ...
- 345