# Search results

1. ### Nonparametric alternative to point-biserial correlation coefficient? - Which? t-test or Mann Whitney?

A. I know from the net that for a design with one binary variable and a second variable that is continuous but is NOT normally distributed, I can use BOTH the point-biserial correlation (which is basically the parametric Pearson correlation formula) as well as the Rank Biserial Correlation...
2. ### ROC curve from an array of Confusion Matrices (true positive rate and false positive rate)

How can us create an ROC curve from confusion matrices?
3. ### A curious design - What is the type / name of this rare design?

There is this split-mouth randomized clinical trial, in which one side of the mouth receives a particular treatment, and the other side receives another treatment (usually used as the control treatment); (we do this after randomization of the left/right sides of the mouth to treatments A and X...
4. ### SPSS - Using mixed univariate ANOVA (UNIANOVA) or mixed linear regression (MIXED) instead of repeated-measures ANOVA

Which process is better for using instead of Repeated-Measures ANOVA (SPSS syntax: GLM -- GUI command: Analyze --> General Linear Model --> Repeated Measures)? and Why? (1) Mixed univariate ANOVA (SPSS syntax: "UNIANOVA" -- GUI command: Analyze --> General Linear Model --> Univariate) (2)...
5. ### Corona hints

Corona Virus - Info from Stanford Stanford Notes on Coronavirus The new Coronavirus may not show sign of infection for many days. How can you know if you are infected? By the time you have fever and/or cough and go to the hospital, the lung is usually 50% fibrosis. Taiwan experts provide a...

7. ### Binary mixed-model logistic regression using lmer() of lme4 for multilevel analysis

In my experiment, each patient has been observed twice, once using placebo and the other time using the real treatment. I want to assess the predictive effects of the treatment and patients' demographics (age, sex, etc.). Therefore I have for example 100 patients, but actually 200 pairs of...
8. ### Univariate, Bivariate, Multivariate: Myths and facts

This is not a question but a summarization of my recent learnings regarding the common mistakes in calling different types of analyses, and to address the proper names for them. I now know that a multiple regression is not a multivariate analysis, although I have seen millions of incorrect...
9. ### Bootstrapped binary logistic regression in R

I am trying to run a bootstrapped binary logistic regression. I have loaded the dataset manually into Rstudio (don't know the syntax yet! actually the syntax I learned from Rcommander didn't work in Rstudio); and here is my code for the bootstrapped regression (thanks to this site): (the...
10. ### What to do when the predictors are not what I expected (when the model is fine)?

I would try to clarify the problem and then ask the questions. The problem (variable names are masked due to confidentiality): I ran a binary logistic regression, in which there were 5 independent variables (IVs): A, B, C, D, and E. A and B are my concern. C is also my concern and I would talk...
11. ### Risk Factors in a Clinical Trial

The study is confidential right now. So I cannot go into the details. But will try to detail every necessary information, in the hope that can get some good advice from you. The design is a clinical trial. We assessed the effect of a material on healing of oral wounds. It turned out to be...
12. ### Contributions to writing code that enable R to analyze the "Descriptive" statistics

Apparently R does use only the raw data. In some other statistical programs, there is the option to calculate some simple tests, only by inputting the descriptive statistics. I for one think it would be much better if we could enable R to run such tests too. There are not many tests that can...
13. ### Is this study clinical trial or retrospective cohort?

Hi We have a set of patients with dental implants in their mouths. We wanna evaluate whether implants in each patient's mouth are as sensitive as normal teeth (of the same patient) to tactile stimuli. So it can be a retrospective cohort, because we have split the sample based on the...
14. ### Can a cohort study have no control groups (is a clinical series study a cohort)?

Hi AFAK a cohort study needs a matched control group. However, its definition doesn't necessitate a control group. Moreover, I have read some publications in which the authors had investigated the complications of some treatments, for example rhinoplasty, during a period of time. They did...
15. ### Is my study case-control or retrospective cohort?

Hi AFAIK if we split the sample by the exposure, it is retrospective cohort; and if we split it by the disease, it is case control. I am studying the association between malocclusion and the efficacy of mastication. I have divided the sample into two groups: people with and without...