# categorical data analysis

1. ### Categorical variables

I have a simple question that I cannot figure out. For a multilevel categorical independent variables (let's say four levels), what is the difference in modelling the variable as 3 dummy variables in comparison with coding it as four levels within one variable in a regression model? Are they...
2. ### Categorical Variable Coding Question

Hi! I have a question on the coding/use of categorical variables: In short, I have two control variables in an SPSS regression model. One is participant (15 levels, or participants) and one other categorical variable (10 levels). And there is just one predictor variable in the model. I've tried...
3. ### analysis for sparse contingency table

I am analyzing a 2x2x3x2 contingency table. The covariates are treatment (2 different kinds, TR1 and TR2, both binary), location of treatment (3 levels A, B, C), and the outcome is an event that either occurred or did not occur. The table is large compared to the sample size, and observing the...
4. ### Interpretation of Mantel-Haenszel Statistics

We have conducted an experiment with 2 groups and a dichotomous outcome on 3 occasions and for each occasion we have a 2x2 contingency table. Rather than pooling the 3 contingency table we want to determine if we have a consistent difference in proportions across the repeats. When we analyze...
5. ### Comparing categorical data for a relationship - alternatives to a chi-square test?

Hi Everyone, This is my first post here, and I am very new to statistical testing, so I'm going to try to make this question as clear as possible (but please feel free to correct terminology, or ask for more clarification if I am missing information in my question). I am working with...
6. ### Comparing two large categorical data sets with low counts

I'm studying a biological feature which can be classified into 2^20 categories. These categories can be thought as a dictionary of a fixed-length words made up from an alphabet, to say, 20-letter words from a binary alphabet. I also have two samples consisting of 3 million and 1 million entries...
7. ### Positive chi-square test: what to do next?

Hi!! I'm analysing two categorical variables, Landslides (YES/NO) and Vegetation (grouped into 18 classes), and I'd like to explore and model the relationship between them. Firstly, I've carried out a chi-square test for independence that has returned a positive result, i.e. the two...
8. ### My nemesis: multinomial logistic regression

Dear all, For the final article of my PhD-thesis, I need to analyze various categorical results. My goal is to find whether a certain genotype will give a predisposition to no, few or many side-effects after taking medication. To ascertain this, I used multinomial logistic regression in...
9. ### Relative Risk Ratio (RRR) Analysis with a Continuous Predictor

Hi, I am hoping that someone can help me with a relative risk ratio analysis. I'm trying to assess the ability of a continuous variable to predict a categorical outcome (the base group - Y) relative to other possible outcomes. The RRR analysis gave me the RRR for the likelihood of outcome A...
10. ### Repeated-measures categorical variables

Hi I can't seem to find a proper way to analyse my data. The study is about associating musical instruments to flavours. I have a repeated measure design: Each participant tastes each flavour (10 total) and picks an instrument (4 choices) for each. I originally used a chi-square test for...
11. ### Categorical variables - Logistic regression

Hello, I am trying to run a logistic regression model. I have 4 numeric and 1 categorical variable which are significant. The categorical variable has 8 levels. I want to bin this categorical variable into 3 levels based on the response. Can I do this? For ex. The new variable has 3 levels...
12. ### Categorical data goodness of fit question

Hello, I am trying to fit a log linear model with proc genmod and when i include all interactions (3 variables) i get the following: Criterion DF Value Value/DF Deviance 0 0.0000 . Scaled Deviance 0...
13. ### Is Chi Square the right test to use?

Dear all, I am having a bit of trouble figuring out which test to perform in the following case: In my eye-tracking study participants are viewing short video clips of people's faces and I count the number of times each of five face regions are fixated by each participant. I have one...
14. ### Did I just fudge this categorical data transformation too much?

I have a public data set gathered from 336 hospitals, with about 28,000 rows. I want to see if there is relationship between a particular input feature, and an outcome, but I want to adjust for which hospital it was collected from. I've tried making dummy variables, but my software chokes...
15. ### Longitudinal analysis - what to do with the baseline data?

Hi, I have posted previously but got no response - so I am trying to narrow my search field down and articulate my questions better. If I am doing a longitudinal analysis looking at the trajectory of a dependent variable (y) over time (x) - but I have baseline measures of y at x=0-1 to...
16. ### What GLM should is use in this dataset?

Hi everyone and thank you! I'm not a student of statistics, i'm in a different but somehow related field. i'm doing this research, been reading books on advanced statistical methods, yet i'm still not sure, if what i've been doing are correct, or if i've used the appropriate methods to tackle...