# Questions tagged [diagnostic]

Diagnostic measures (such as residuals or some summary statistics calculated from residuals) are used to evaluate some aspect of quality of model fit to data.

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### Two diagnostics tests over time

I have the following problem. I want to compare a self-diagnostics tool (questionnaire based) with a gold standard diagnostic tool. However, I have the following issues: 1- The gold standard is not ...
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### combine Accuracy of two diagnostic test

How can one calculate combine accuracy of two independent diagnostic test on the Same population to increase the diagnostic accuracy
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### Diagnostic plots GLM [duplicate]

I done a binary regression,it's possible that the the plot of residual vs Predict has two different line? I never see before one like this
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### problem with diagnostic plots for binary regression

I make a binary regression to study Italy's poverty/non poverty on R. mod1<-glm(status~CLETA5+cit+AREA3+Q+studio+ACOM5+godabit,data=total,family=binomial) I don't know if the diagnostic plots are ...
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### rstandard vs stdres have different behaviour (the hat matrix)

To obtain the standardized residuals in R, the the residuals minus their mean are divided by their standard deviation (calculated with the model degrees of freedom). It is also calculated using the ...
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### Why we do acf on residuals?

In the book "Time series analysis" by Shumway. He is doing fit = lm(chicken~time(chicken), na.action=NULL) acf(resid(fit), 48, main="detrended") What is the ...
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### Interpreting Regression Diagnostic Plots

I'm sorry if this is a broad question but can someone explain to me how to interpret these regression diagnostic plots? I understand the Normal Q-Q show's how normal the spread of the data is, but the ...
119 views

### GAM using a cyclic spline improves residual structure but reduces fit

I'm working on a dataset monitoring soil moisture levels throughout the summer. The general trend in the data is the following: When I use a GAM with default thin-plate spline and AR(1)process there ...
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### MCMC - Diagnostics plots

I am currently using MCMC for Bayesian Inference and am now plotting diagnostics plots. While I understand what I am looking for in a trace plot, I am not so sure about the cumulative quantile plot ...
567 views

### How can I check model assumptions in AFT survival model?

I am working with interval censored data and I am fitting an AFT model with the survreg() function from the survival package. ...
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### Failing to implement Bayesian Chi2 goodness of fit test

I am trying to implement one of the methods described in Valen Johnson's A Bayesian Chi-Squared Test for Goodness of Fit. It presents a couple of variants depending on whether the random variable of ...
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### CUSUM test for a Nonlinear Regression Model

I would like to do a CUSUM test for the regression parameters of a nonlinear regression model to analyze possible parameters variations. For linear regression models the CUSUM test is based on the ...
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### Linear regression very significant βs with multiple variables, not significant alone

Could anyone provide intuition on why for y ~ β1x1 + β2x2 + β3x3, β1 β2 and β3 can be significant in a multiple variable model (p range 7x10-3 to 8x10-4), but the βs are not significant in separate ...
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### estimate probability that sensitivity/specificity greater than threshold value

Is there a Bayesian method to estimate the probability that the sensitivity of a diagnostic test is greater than some value, say 0.70? Rather than estimate sensitivity and a confidence interval (e.g., ...