Questions tagged [medicine]

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What statistical method am I using in this study? [duplicate]

I am new to statistics and I need to know how to describe the statistical model of this study in my abstract. A retrospective medical study assessing the risk factors predisposing someone to a an ...
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30 views

What statistical model is this study using?

I am new to statistics and I need to know how to describe the statistical model of this study in my abstract. A retrospective medical study assessing the risk factors predisposing someone to a an ...
1
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0answers
24 views

Is the shrinkage of subgroup analyses in meta-analysis an example of Stein's paradox?

This paper writes (edited for concision): Consider, a doctor in Germany confronted by a meta-analysis of long term‚ $\beta$ blockade after myocardial infarction. Although a robust beneficial effect ...
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1answer
23 views

Would “correcting” for patient characteristic in a cohort study always strengthen the study?

If we are doing a cohort study and investigating whether a variable has an effect on an outcome (say tumor size on nausea), and we run a regression (or chi2) with nausea as a dependent variable and ...
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1answer
9 views

Unsupervised Odd-one-out - paper recommendation

Abstract Problem: I have several series (sharing the same class) of about 400 small images each. Each one of my series has >390 images, that belong together. The rest of the images shares the style of ...
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1answer
28 views

Admissions per year before and after antibiotics?

I need to compare hospital admissions per year before and after the introduction of antibiotics in 100 patients (antibiotics introduced at various time points in the past). Eg. Before antibiotics: ...
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15 views

Looking for statistics suggestion for data set: EEG “Diagnostic” measurement comparison - non-parametric/ordinal - large proportion of zeroes

I was hoping to get some input on handling a particular data set that falls outside of the purvue of the a lab I am apart of (usually outcomes research). The data consists of a pair of repeated ...
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6 views

Picking variables to proceed with in a “shotgun” type of study

In medicine, we often have a question such as "I wonder if any of these variables have an effect on the health of these patients". In short, we don't really have a solid hypothesis, we just want to ...
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35 views

“Unselected sample” vs “random sample”

I've just encountered the term "unselected sample" for the first time, which seems to be fairly commonly used in medicine. Example usages: Climacteric symptoms in an unselected sample of Swedish ...
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1answer
23 views

number of samples needed to show difference between two samples

I am an opthalmologist not trusting what the drug companies are telling me so need some help I am looking a papers on glaucoma where the pressure of the eye is measured. The SD of the measurements is ...
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1answer
67 views

Visualization associations between the symptoms - categorical data in R

I have a data frame with presence of symptoms which are categorical data (1 = present, 0 = absent). For instance: ...
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60 views

book recommendation - statistics in medicine

Could you recommend a book about the implementation of basic statistic concepts in medicine? In particular, I want to find a book that covers principal component analysis, correspondence analysis and ...
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0answers
14 views

Significance test for Patient Years

Previously, I had a question about CI for Patient-Years (py) and there was a great answer from @TamasFerenci. Now I need to find out the $p$ value for the py of two different groups. I have a table ...
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2answers
131 views

How to get confidence intervals for Patient-Years?

In medicine patient-years is a popular concept. Example: $100$ patients are followed for $2$ years. In this case, there are $200$ patient-years in total. If there were $8$ myocardial infarctions in ...
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0answers
15 views

How to analyze time series data with very few samples for response variable

I want to use R to model a person's blood-iron level to predict how it changes over time. My response variable is blood-iron level and my explanatory variables are related to diet, use of different ...
3
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2answers
61 views

Medical efficacy confusion

On this page one can find the following statement: Magnitude of Effect: Vaccination against HPV-16 and HPV-18 reduces incident and persistent infections with efficacy of 91.6% (95% confidence ...
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42 views

Particle filter for diagnosis

I have two annual measurements taken on medical images depicting a lung cancer tumor 's condition. I have likelihood function that taken in the measurement values and estimates malignancy of the tumor....
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0answers
29 views

How do I divide a density/frequency plot?

I have a frequency plot, which is essentially a smooth histogram. There are three very clear features (divided with a line by eye). Please note, there are two groups, male and female. The data used to ...
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1answer
79 views

Ordinal regression or multiple regression?

I'm using STATA and this page to find a proper test, but I'm not sure which is better fitting, an ordered logistic regression or multiple regression? My dependent variable is life quality (ordinal ...
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0answers
19 views

Compare change between 2 timepoints with two (paired) variables for paired subjects

This was a difficult question to search for, so my apologies if it has already been posted. Hi, I have the following data in R: I ...
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1answer
23 views

Why are likelihood ratios weighted for prevalence?

I notice LLR's are weighted for prevalence if the prevalence differs from 0.5 (see: http://vassarstats.net/clin2.html) Can someone explain why this is? I'm a medical student, not a statistician, so I'...
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6 views

Can I estimate a new post-test probability?

Let's say a patient, let's assume a pre-test probability of 20%, gets a test done with a positive predictive value of 70%. He tests positive. He gets another test done, which has a positive predictive ...
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1answer
39 views

Is this test muddying the water?

In the case of a neurological disease called idiopathic normal pressure hydrocephalus, if the patient is suspected positive for the condition, they are administered a test called the spinal tap test. ...
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21 views

Statistical testing in clinical research

I just did a univariate binary logistic regression to classify a disease based on some medical parameters. Now only one variable showed significant result (p-value < 0.05). Assuming sufficient ...
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0answers
11 views

Demonstrating improved agreement on clinical decision making using the Kappa coefficient

I have a large number of respiratory doctors - some from University hospitals and some from community non-academic hospitals. They have been asked to evaluate 60 patients with various different lung ...
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1answer
30 views

How to compute Nth percentile data from other percentile data of a normal distribution?

I am trying to compute the 98 percentile value of a normal distribution data set. The data is from this website https://www.cdc.gov/growthcharts/percentile_data_files.htm, file No.8 called "BMIAGE". ...
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0answers
31 views

Seeking statistical approach for prediction: (categorical, quantitative) -> quantitative

I am trying to find a good statistical approach for predicting a quantitative outcome from composite variables consisting of a categorical variable and a quantitative variable. Specifically, I want ...
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20 views

“Matching” groups in a clinical study

I have the following question regarding a clinical study in the Surgery department of an hospital: 1) I have two groups of patients: group A - comprising patients operated in 2016; group B - ...
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25 views

How to compare predictions made by two different models?

Please help me understand this: There's something called the MAGGIC Risk Calculator for Heart Failure for predicting adverse outcomes in patients with heart failure....
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34 views

Statistics in medicine, any literature recommendations?

I work in the field of medicine as Ph.D. student. My primary work right now is modeling. And the more I get into it, and its statistics, I can see that I lack a lot, and what I have done, and others (...
3
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1answer
222 views

Univariate or multivariate regression for this project?

I'm looking at the risk of seizure in patients with metastasizing brain cancer and so far have several variables that I want to check to my dependent variable of seizure yes/no. These are variables ...
1
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1answer
56 views

ICD10 (categorical) encoding

I am trying to figure out how best to encode ICD10 codes for input into a machine learning model. It isn't ordinal by any means, however, there is a sort of logic you can apply to just the labels ...
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0answers
31 views

Inferring incidence from prevalence

I have a data set of patients with a risk factor for disease "A", which can be of grade 1, 2 or 3. The grade is determined by a lab value, i.e. Healthy <20, <...
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0answers
9 views

Choice of model for prognostic value of asymptomatic recurrence detection

I am involved in the final step of a project that evaluates the prognostic value of asymptomatic vs. symptomatic recurrence detection; all subjects experienced recurrence. The project proposed a ...
1
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1answer
88 views

What is exactly 30-day post procedure period?

In medical literature early adverse events are often counted for 30-day post procedure period. I was sure that the period's days are as follows: day of procedure, 1st day after, 2nd day after, ..., ...
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0answers
18 views

Deliberately creating unbalanced class size

I'm working on a logistic regression model to predict a certain disease, binary classification (Present/Not_Present). The disease has a normal occurrence rate of about 10% in the general population. ...
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1answer
22 views

Dealing with Varability in Predicting Deaths

I hope this is the best place to ask a question like this and will not be to vague for this type of forum. I am hoping for some corrective guidance with an issue I am having. I work for a non-profit ...
4
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1answer
973 views

Chi Square versus Poisson distribution

In a study which analyses the effect of Lithium on suicide rates, the results were the following: Placebo group: 3 suicides in 83 patients Lithium group: 0 suicides in 84 patients My first approach ...
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0answers
22 views

Matching inflation

I have data on a few millions of patients, about 1000 of them are cases, that is, they were diagnosed having a certain disease at some timepoint in their life. I think I basically have two options: 1)...
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0answers
35 views

Adequate choice of T-Test

I have a question regarding comparability of t-test variants. The experimental set-up is the following: Comparison of Gene Expression Level of gene x between condition a and b. The conditions ...
2
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1answer
70 views

Convert classifier output for disease to probability using Bayes

Method 1 I am given a classifier for some disease that takes as input patient characteristics and has some sensitivity and specificity. Hence the classifier is a function c(patient characteristics) ...
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3answers
606 views

Machine learning on small datasets

As a beginner at machine learning, I wanted to work on a small project in which the dataset has only 80 rows and 5 columns. The dataset I am working with is related to a medical condition, with 4 ...
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0answers
85 views

Predictive model for a disease based on observational data---effort in futility?

Suppose I have observational data and want to predict some disease based on patient visits. In each visit I know whether the disease occured. The disease is preventable (which is why I want to ...
2
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1answer
2k views

What might a correct approach be, to image preprocessing for CNN for these specialised images

I am trying to understand the the best practices for preprocessing images prior to neural network training and I have some uncertainties despite reading extensively online about it. I am also ...
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46 views

Linear regression with a dependent variable that is mathematically related to an independent variable

Background I have clinical study data from 500 subjects. Measured variables (measured once in each subject), among others: $P_s$: Systolic blood pressure $P_d$: Diastolic blood pressure $d_s$: ...
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1answer
353 views

Interpret odds ratios of ordinal independent variable in logistic regression

I have a set of data where I would like to do logistic regression modeling the odds of a binary outcome variable (Therapy), with Stage as an ordinal explanatory variable (0,1,2,3,4). I am using SAS. ...
2
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1answer
101 views

Univariate and multivariate regression

I found a research article Nurses’ reports of staffing adequacy and surgical site infections: A cross-sectional multi-centre study and I want to know the reason why they used regression for their ...
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0answers
47 views

Bayes' theorem in a medical context

Imagine an essentially random, very large population of people (say 50 million individuals). A given subset of them have a disease 'D'. By inspecting this subset, we observe that 40% of the people ...
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2answers
390 views

wilcoxon mann whitney or t-test?

I would like to compare the number of a particular type of disease that is prevalent in men vs women. The number of diseases is interval data (0,1,2,3,etc). Should I use the wilcoxon mann whitney or t-...
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2answers
73 views

Very easy question. Please help

Very easy question for medical research. I have a group of 45 sick people of which 20 western and 25 non-western. My hypothesis states that there should be no difference between western and non-...