# Tagged Questions

Categorical data can take on a limited (usually fixed) number of possible values called categories. Categorical values "label", they do not "measure". Nominal and dichotomous/binary scale types are categorical. Some people consider ordinal scale categorical too.

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### McNemar's test p-value NA

I have paired data from 9 individuals. The response variable is ordinal with levels 1-5. As the sample is very small and the data are categorical, I thought the appropriate test was McNemar's test. ...
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I have drawing data from 10 subjects drawing 8 shapes (and many repetitions of every shape). I fitted a model to this data Matlab, separately for each subject and each shapes, such that I have 2 model-...
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### Where to find a guide to encoding categorical features?

I am facing an ML task with various categorical variables. Some examples include the following: Binary variables (0,1). Multilevel factors that can be ordered (low, medium, high). Multilevel factors ...
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### How to reduce the number of labels in regression

I'm working in a regression problem, related to bio-signals, where my labels are integer numbers between 0 and 10. I've tried a couple of regression algorithms already, mainly linear regression. Edit:...
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### What method for classification with 24 variables, 14 categories and 100,000 obs.?

I have a dataset with more than 100,000 observations (rows) and 24 variables in which 23 are continuous and one is categorical variable. The categorical variable has 13 categories (1, 2, 3, ..., 13) ...
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### Validation for Household Relocation Model without validation set

We are working on several household relocation models based on census data. This data contained the location of many households over the course of three years, along with several other variables. The ...
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### Confidence interval for Bayesian expected probability in categorical data

The context of the question is survey results analysis. I am focusing on categorical data : N respondents answer some questions and each question has $k_{q}$ choices. I want to compare what subgroups ...
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### Cumulative link model with categorical or continuous predictors?

I have data in a perception experiment where I show surfaces slanted at different angles and ask participants to judge whether the surface could be stood on. I also asked them how certain they are ...
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### In medical statistics, when to use $\chi^2$ and when to use Kruskal-Wallis H?

I am conducting a retrospective analysis on the effect of three different treatment option (intervention treatment) on a special type of cancer, so I have three groups: 1, 2, and 3. In the baseline ...
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### Does selection of predicted vs. reference class matter in hierarchical multinomial regression?

A simplified example: There are three classes: $1$, $2$ and $3$. They have a natural order, i.e. $1<2<3$. I have a different number of observations of the classes, e.g. $1$ has been observed ...
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### How to prepare data to analyze two values simultaneously as one

as a newbie in statistics I'm having trouble with preparing my data. I have data where a measure is performed on left and right side. When comparing group means I need to take simultaneously both ...
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### R - create list with levels [migrated]

I have a dataframe with large number of categorical variables. I need to create a list, where I would get the output similar to str(DF), but not truncated Example: ...
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### How to model turnover as a function of square meters?

After some study I came up with the following regression structure for a model with turnover as the dependant variable and square metres as the independant variable (and some others, but I don't think ...
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### Performing limma on residuals or including batch and other covariates in the model?

I am trying to analyse a gene expression dataset of about 240 samples (Illumina microarray). There are multiple questions I need to ask (healthy vs diseased, effect of treatment in diseased, ...
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### Which measure of inter-rater agreement for multi-class rating

In our experiment subjects could choose up to three values from a list of 18 categorical values. So let's say that the classes are animals: cat, dog, mouse, sheep... And that the subjects were asked ...
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### One-hot vs dummy encoding in Scikit-learn

There are two different ways to encoding categorical variables. Say, one categorical variable has n values. One-hot encoding converts it into n variables, while dummy encoding converts it into n-1 ...
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### R: efficient way to apply a function according to the columns of a dataframe [migrated]

I feel extremely stupid now but I can't come up with more than a for loop... I have a data frame with numerical and factorial columns. I simply want the numerical columns to be scaled and the ...
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### Association of qualitative and quantiative variables

I have data of an ordinal qualitative variable and I would like to study if it has some relation with a continuous quantitative variable and I don't know what technique could I use for that. I was ...
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### Data preparation of a new record on the fly [migrated]

I am facing problem in the implementation of Data Preparation of a single record on the fly. I am loading the model from disk and I need to to make prediction against it. Lets Say, I have 3 ...
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### Is multinomial logistic regression appropriate for a dataset containing categorical data with small cell counts?

I'm analysing a large dataset from a questionnaire with 560 respondents. A cluster analysis performed based on coded free-text data resulted in 11 mutually exclusive clusters. Based on explanatory ...
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### Test for ordinal repeat measure data with multi level response categories

I want to find the relationship between parameter setting of medical images and the visibility of the organs in images. I also want to see if the organ visibility in the test images are significantly ...
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### Before-after analysis of categorical data

I have carried out an experiment, during which the participants tried several authentication methods; as well as a pre- and post-survey, which measured the participants' familiarity and adoption of ...
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### Input missing values in categorical time series

I have a dataset similar to ...
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### How can I quantify unordered categorical data with infinite possible outcomes?

I'm trying to model a very simple supervised machine learning model. Let's say that it's a logistic classification problem. I must take into account some qualitative variables (categories) with a ...
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### How to show association between categorical variables with graphs?

I have 4 categorical variables in a dataset let $X_1$, $X_2$, $X_3$ and $Y$. Where $X_1$,$X_2$ and $Y$ is a binary random variable and $X_3$ have 3 categories. How can I study the association of $X_1$...
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### Poisson Regression model in example

I need to fit a model to study the severity of bicycle accidents. The data description is $X_1$: is the use of helmet, a categorical variable (1=Yes,0=No) $X_2$:the speed at which he was riding, a ...
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### Baseline for dummy variables in XGB. Is it important?

I have a lot of categorical variables that I am using in an XGB model. I use the package dummies to make dummy variables and it creates dummies for all levels. There is no baseline. I know that in ...
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### One video, four overlays with X options each, how many possible generated videos?

We have a video where we want to overlay four images to generate a custom video. But each image has X number of options. So we are trying to determine how many total possible videos could be ...
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### An appropriate alternative to chi2 for paired, categorical data (tables larger than 2X2)

I am analysing a data set consisting mostly of categorical data. This has resulted in a number of contingency tables (mostly, but not always larger than 2X2) that need statistical testing. Now, I ...
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### Presenting logistic regression tables for non-binary categorical variables (Stata)

For my logistic regression model I have a couple of non-binary categorical predictors (e.g income level and education) with more than three categories. My question now is how to present findings for ...
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### Reporting a reduced regression model with an “incomplete” set of contrast codes?

I have included a categorical predictor (4 response styles) in a regression analysis using the following set of contrast codes: I am only interested in contrast V3 (Style 1 vs. Style 4) as it ...
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### Logistic regression variable selection methods

I'm having trouble to understand Backward elimination in Logistic Regression model. I was looking at this example of Agresti, Categorical Data Analysis, to see how Backward elimination works. What ...
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### Same kernel for mixed/categorical data?

I know it's common practice, but is it right to apply the common kernels to categorical/mixed data? If not, are there alternatives? I'm expecting answers from both theoretical and practical points of ...
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### Dealing with Unbalanced categorical data for prediction in R

I'm currently working on a predictive model concerning a dataset of 180521 observations for ~10 variables (including the predicted class). The predicted class is caracterized as below : True : 8058 ...
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### How to visualize classifier output?

Problem description: I have an Excel sheet containing a table of true and estimated values. I want to somehow capture this information over a plot of actual (horizontal axis) vs estimated values (...
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### Multilevel nominal variables in regression

Can I use multi-value nominal variables as random coefficients in a multilevel regression model with an intercept included? For example: ...
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### What if two dummy levels does not have constant variance

I am trying to use a binary dummy variables in my multiple linear regression. I have tested the identical slope assumption and it is confirmed. However, I did a side by side boxplot of the two levels ...
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### Goodness of fit test for categorical data with non-negative real numbers

An experiment that I conduct has 5 outcomes: A, B, C and D. I conduct 12 trials for this experiment. I observe, for example: Outcome Frequency A            &...
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### Identical variable importance values for different model types

I trained two different caret models on the same multi-class training data using repeated cross validation and computed the variable importance. What strikes me, is that for both models varImp returns ...
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### Variance of a distribution of multi-level categorical data

I am currently analyzing large data sets with various characteristics (such as city). I wanted to find a measure which would essentially say how much or how little of a variance there was across the ...
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### Dummy coding vs. continuous variable in regression analysis

I am doing a regression analysis in R, in which I examine the contribution of each car attribute to its price. Some variables can be coded as a dummy variable, or as a continuous variable. For ...
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### Correlation between an independent continuous variable and a discrete dependent variable

I have to find a correlation between a numerical continuous dependent variable and a dependent variable which is the 'Number of User's Actions'. As you can figure out this variable gets integer values....
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### Test for determining likelihood of finding disease in 1 of 2 lymph nodes in patients with cancer

I am performing a study looking at two specific lymph nodes in the head and I want to be able to say if disease is more likely to be present in 1 or the other lymph node. Also, if disease is present ...
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### Correlation multinomial distribution

Problem 1.14 from Categorical Data Analysis 2nd. For the multinomial distribution, show that $$\operatorname{corr}(n_j,n_k)=\frac{-\pi_j\pi_k}{\sqrt{\pi_j(1-\pi_j)\pi_k(1-\pi_k)}}$$ Show ...
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### R - analyzing 2 by 2 table of categorical data

I have a small data set of cases from an outbreak. For each case I have collected data for a few variables (age, HIV status, hospitalisation, country of infection etc. ). There are only 28 cases and ...
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### Regression with some observations having more than one factor level

I have data I want to analyze using multiple regression or machine learning: the response is cells for which I measured viability (a continuous response) and the independent variables are the genes in ...
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### Reducing variable candidates for multivariate regression step by step

I have a set of possible candidates that I want to use in a multivariate regression. I am trying to reduce this set by the following procedure (using Stata): Step 1: univariate regression (if ...
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### What statistical test should be used to compare two independent sample over time (pre- and post-test) for categorical variables?

I have baseline and follow-up surveys, asking the same 33 questions. A typical question is: How well do you think your family knows what you are good at? Very Well Well ...
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### how to deal with panel data with categorical variable in regression

I have got a panel data regarding to electric consumption(including total consumption,AC consumption and light consumption) among different buildings.There were categorical variables I have already ...
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### 2X2 Factorial Design with Likert-type Responses

I have a 2x2 design completely between subjects. Both independent variables are dichotomous. The dependent variable is a 7 point Likert-type item. But I'm not sure how to analyze it. I know ANOVA, ...