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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Diagnostics for generalized additive model vs linear model

I am doing an analysis in R and I have the model: lm(birthrate~education+employment+lo(latitude, longitude),data=data2). It seems to be a generalized additive ...
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14 views

Diagnostic Tests with Panel Data [on hold]

With a cross-sectional regression, there are several diagnostic tests that I know how to conduct in Stata. For example: - To identify heteroskedasticity, I use estat hettest - To identify whether I ...
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19 views

How to interpret diagnostic plots for GEV distribution

I produced the following Diagnostic plots, from the following R Code: ...
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41 views

Are these diagnostic plots from lmer too far away from normal and showing heteroscedasticity?

I have read similar posts in this website to help me assess whether my diagnostic plots are too far away from normal and if they are showing heteroscedasticity (Interpretation of residuals vs fitted ...
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76 views

what to do with ridiculous but valid leverage points

So I'm having some difficulty fitting a linear model to the data (see other post here glm model fit - can't find a family/link combination that produces good fit). In particular, I'm worried ...
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173 views

Prove the relation between Mahalanobis distance and Leverage?

I have seen formulas on Wikipedia. that relate Mahalanobis distance and Leverage: Mahalanobis distance is closely related to the leverage statistic, $h$, but has a different scale: $$D^2 = (N - ...
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312 views

Interpreting case influence statistics (leverage, studentized residuals, and Cook's distance)

I just wanted to clarify some things about leverage, studentized residuals, and Cook's distance: Does a large (in absolute value) studentized residual mean that a case is an outlier? Does a large ...
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67 views

Mixed model or ANOVA on differences in pre-post design

I want to analyse the effect of different treatment types (control, treatment1, ..., treatment4) on the surface of specimens made of certain materials (...
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12 views

Autocorrelation of MAPE in case of lack of autocorrelation in residuals?

I'm building a forecasting tool for electricity market (spot power market). The model forecasts spot prices of power for each of 24 hours of next day. I measure its performance for whole days (for 24 ...
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21 views

Standardized residuals vs fitted values for Poisson regression

McCullagh and Nelder's book on glm suggest to plot standardized deviance residuals against either the linear predictor ($\hat{\eta}$) or the fitted values ($\hat{\mu}$) transformed to the constant ...
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2answers
85 views

Which is the best method for meta-analysis of diagnostic test accuracy studies?

I am conducting a meta-analysis of diagnostic test accuracy studies focusing on myocardial perfusion imaging. I have used first Meta-Disc, but only for descriptive purposes, as it is clear that ...
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20 views

Lag length for the Ljung-Box test

I have an ARIMA model applied on hourly data: Arima.fit2 <- Arima(tsTrain, order=c(17,1,0)) The length of my training set is 60 hours. In the end I plan to ...
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48 views

Confidence interval of AUC with Reitsma model in mada R package

I am conducting a meta-analysis of diagnostic test accuracy studies comparing myocardial perfusion scintigraphy vs coronary angiography using the mada R package. I ...
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14 views

When creating a multiple regression model for a subgroup, is it necessary to test all assumptions again?

My results section consists of a multiple regression analysis considering 3 factors, containing all of my participants. Following this, I have considered males and females separately, by construction ...
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59 views

GARCH diagnostics: autocorrelation in standardized residuals but not in their squares

Fitting an ARMA-GARCH model, I checked the Weighted Ljung-Box test on standardized residuals and squared residuals to verify if the model is adeguate in describing the linear dependence in the return ...
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25 views

How should I interpret/follow-up on mixed logistic regression (GLMM) diagnostics?

I have experimental data (n subjects = 64) in which the response variable, accuracy (0 or 1), was measured 9 times within subjects. My predictor is Condition (A vs B) measured between subjects. I ...
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16 views

Assessing the residual independence assumption (nonlinear least squares regression diagnostics)

I would like to assess the assumptions underlying nonlinear regression models using statistical tests rather than graphical methods since I have thousands of fitting results. I am not certain ...
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11 views

How to decide between quasi-poisson and negative binomial?

I tried quasi-poisson and negative binomial glms on my counted data in R. The estimates are pretty much the same but p-value are different. Quasi-poisson gives insignificant result. NB give ...
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1answer
116 views

GARCH model diagnostics: how to interpret test results?

I'm new here and also new in Ox environment. Those below are results I obtained from estimating AR(5)-FIGARCH(1,$d$,1) models. ...
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Same error on all sets

My concern is the classification of data splitted into training, cross validation and test sets. By evaluating my model, the values of precision, recall, f-score and auroc are nearly the same for all ...
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33k views

How to read Cook's distance plots?

Does anyone know how to work out whether points 7, 16 and 29 are influential points or not? I read somewhere that because Cook's distance is lower than 1, they are not. Am, I right?
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44 views

Posterior predictive checks and the real world

In general, when performing posterior predictive checks, one calculates a posterior predictive p-value like so: $$p_B = \frac{1}{S}\sum_{s=1}^{S}\mathbb{1} (T(x^{(rep,s)},\theta^{s}) \ge ...
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1answer
56 views

How to identify outliers and do model diagnostics for an lme4 model?

I need to identify outliers and high leverage points, and perform model diagnostics, in an lme4 model. For outliers and high leverage points, simply making a plot ...
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97 views

Statistical tests for comparing Positive/Negative likelihood ratios in two independent diagnsotic tests

I have a problem regarding the comparison of the likelihood ratios in two diagnostic tests. The definition of positive likelihood ratio in screening tests is "the probability of a person who has the ...
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50 views

Tilted rectangle in residuals vs fitted plot

When performing diagnostics on an OLS model, what can make a plot of the predicted responses vs the residuals. Ideally we want a horizontal rectangle shape. But what does it mean when the plot is a ...
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44k views

Likelihood ratio test in R

Suppose I am going to do a univariate logistic regression on several independent variables, like this: ...
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GLM Diganostic Analysis - What plots actually matter?

In regards to this Poisson approach (How can the Poisson GLM be used instead of logistic regression for the Titanic survival data?). I always thought that Normal Q-Q, Cook's D distance plots were ...
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Diagnostic measure not influenced by transformations of response variable

What are the diagnostic measures (like Cook's distance, H matrix, DFFITS, DFBETAS) that are not affected by the transformation of the response/dependent variable? And why?
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Logit model simulation - binned residual plot seems to exhibit bias

To understand how to perform diagnostics, I've been experimenting simulating logit models. The binned residual plot makes sense to me as a simple way of analysing whether residuals are distributed as ...
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58 views

Evaluation of diagnostic test ($R^2$ vs AUC)

A sort of a risk evaluation system is offered to us (sort of advertising). The output value is lethality (yes/no). The evaluators are several diagnoses, emergency status, age etc. No detailed ...
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38 views

Positive predictive value versus false positive rate

A colleague of mine has quoted to me the following: For a given population with a known specificity and a known event rate where a positive test is thought to predict the presence of an event: ...
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1answer
21 views

Is Box and Pierce test on residual or squared residual?

In a GARCH model, is it better to test the autocorrelation of squared residuals rather than the autocorrelation of residuals? Thanks!
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2k views

How to manually calculate dfbetas

I am trying to replicate what the function dfbetas() does in R. dfbeta() is not an issue... Here is a set of vectors: ...
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65 views

Diagnostics for quasipoisson glm for continuous data

I'm a little confused about how to use the quasipoisson family in the glm function. It was recommended by someone that I use it for my analysis, even though the data are continuous - and as such, I ...
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57 views

Why is my logistic regression fit that bad?

I was requested by a professor to analyze a high dimensional dataset (92 cases, 400+ variables, and a lot of NAs...) of various patient outcomes (gaussian distributed, counts, and binary) and their ...
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Is there a test for omitted variable bias in OLS?

I am aware of the Ramsey Reset test which may detect nonlinear dependencies. However, if you just throw out one of the regression coefficients (merely linear dependencies), you may get a bias, ...
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Residual Diagnostics and Homogeneity of variances in linear mixed model

Before asking this question, I did search our site and found a lot of similar questions, (like here, here, and here). But I feel those related questions were not well responded or discussed, thus ...
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26 views

Logistic Regression Diagnostics

I am a bit confused how to assess the results of a logistic regression procedure I ran. Using SAS (on a 60% training set) - The LRT, Score and Wald test and got very low p-values. However, this model ...
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32 views

Problems in finding outliers and leverage points in non-linear regression

I'm implementing diagnostic of non-linear regression model $(y=ax^b)$. I'm trying to find out where outliers and leverage points in my model ...
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1answer
15 views

How can model misfit introduce dependency?

I read somewhere recently that mis-fitting a regression model can introduce dependency into the model. Unfortunately I cannot find the where I read this. Can anyone explain how mis-fitting a ...
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119 views

ARIMA diagnostic testing in Stata

I am using an ARIMA(1,1,0) in Stata. I have already executed estat aroots and wntestq (white noise test) for the residuals. I ...
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18 views

Diagnostic plots for logistic regression [duplicate]

I want to check for the assumptions of linearity in my logistic regression model, which states that the logit of the probability is a linear combination of predictors. It might be the case though, ...
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53 views

Zero-inflated models how to get predicted values = 0 stata

I'm fairly new at Stata and this is the main reason of my question. I did a longitudinal zero-inflated poisson model: ...
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19 views

Does it make sense to standardize residual using $SSE/(n-1)$?

See[Dean and Voss]Design and Analysis of Experiments,1999. pp.105 The authors proposed that we standardize residuals using: $$z_{it}=\frac{\hat{e_{it}}}{\sqrt{ssE/(n-1)}}$$ where ...
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63 views

Using Half-Normal Plot to Identify Outlying Observations

When we perform linear regression diagnostic, we usually utilize the half-normal plot (available in the faraway package in R) to identify outlying observations. ...
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84 views

When is it justified to “peek” at the outcome variable in model-building process?

I am referring to the following comment made in a 1996 paper by Dr Frank Harrell et al in Statistics in Medicine: Unless a formal penalized estimation technique is used, multiple comparisons ...
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68 views

Tukey Test in Linear Regression Model Development

I am not able to interpret properly the Tukey Test results from a linear regression model i have built. The Tukey Test for the model i believe is to test is the model is linear. Please correct me if i ...
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2answers
155 views

What does 8.6e-28 mean in the result from a White Test testing for heteroscedasticity?

I used a White Test for testing the homoscedasticity assumption of the linear regression I am working on. I have a problem with the interpretation as I have a result from the test in which the p-value ...
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29 views

Externally studentized residuals

Assume the our model is simply $$Y = X\beta + \epsilon$$ with $\epsilon$~ $N_n(0,{\sigma}^2I)$. If we want to identify the existing outlier in our dataset, we use the externally studentized ...
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432 views

How to compute sample size to compare two diagnostic tests

I will be performing two diagnostic tests (one is the gold standard, one is novel) on the same subject aiming to establish sensitivity, specificity, PPV and NPV. What formula may be used to compute ...