The science of statistics applied to the analysis of biological or medical data.

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ANOVA on Delta Percentages

I would like to validate the effect of some drugs on a certain parameter in my cells. With the first drug, the parameter will go up, while with the second il will go down. The measurements have been ...
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10 views

Applying paired t-test to compare averages

So I did an experiment for 1 month where I investigated the change of pH of 3 different types of milk in the refrigerator and room temperature. I d now like to compare the results of each type of milk ...
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39 views

bio statistic question in epidemiology [closed]

A cancer screening test is being applied in a population of 200 men who were also evaluated through the biopsy of tumor. 30 of the men were confirmed having cancer through biopsy. Out of these 30, 25 ...
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46 views

bio statistic question in epidemiology [closed]

An epidemiologist in Saudi Arabia wants to study the efficacy of iron supplementation for the prevention of HIV infection. He wants to make sure that only subjects who are free of HIV infection are ...
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7 views

A rate model for sodium channels

I am studying by myself Human Physiology. I have encountered the following question: In the following given model of sodium channel with 3 states open closed blocked (which I assume means ...
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50 views

computing sensitivity, specificity, Positive predictive value and Negative predictive values of the test for presence and absence of the disease

A cancer screening test is being applied in a population of 200 men who were also evaluated through the biopsy of tumor. 30 of the men were confirmed having cancer through biopsy. Out of these 30, 25 ...
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1answer
18 views

What is the meaning of gradient & progression rate?

Event Rates Over Time for a 60-Year-Old Patient With Baseline Peak Aortic Valve (AV) Gradient of 25 mm Hg and Progression Rate of Aortic Stenosis of 5 mm Hg/Yr I have following questions: Q1. Does ...
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10 views

Is it valid to combine multiple columns for t testing when n is small?

I have measured one variable from 6 different samples each in three different patients. The 6 samples come three apiece from two different anatomic sites (blood and gut). I would have liked to use ...
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14 views

Mutations in known DNA sequence: which test to use?

I am analysing a double knockout (mouse), and trying to see whether restoring one or another of the genes it's missing affects specific positions preferentially in a third gene. The data* looks ...
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20 views

Given a biological dataset with measurements over a year, how can I identify seasonal variation, if any?

I have a biological dataset and I am interested in answering the following question: Are the measurements dependent on time-of-year/season? I use R for my analyses
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28 views

Tukey's test of additivity or Tukey's one degree of freedom test

Does anyone know anything about this test? I have a scale of 9 questions and I don't know how to explain Tukey's test of additivity or Tukey's one degree of freedom test. How to report this test and ...
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4 views

KAP survey: Best possible choice of analysis

What is the best way of doing data analysis for a KAP survey? Need to analyze the Teffect of intervention (health education) between the pre and post survey. Knowledge attitude and practice of 3 ...
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20 views

How to find the posterior distribution and posterior mode of Beta given an exponential prior distribution and binomial data?

This is the question I'm working on: I have already completed part (a). For part (b) i, I modeled y1 given Beta and n1 as Binomial(n1, p1 = d1/(d1+Beta)). For part (b) ii, I showed that the ...
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11 views

Variability of the reference data and its effect on the transformed values

I conducted a study to compare two different tests at two different ages (children). Based on the previous literature we had hoped that the scores should be better (low score) with age but this was ...
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13 views

Difference between Discrimination, Calibration, Accuracy and Precision

I have trouble understanding these terms: a.) Discrimination. b.) Calibration. c.) Accuracy. d.) Precision. I really get confused with the books I am reading, ...
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3answers
839 views

Statistical methods for data where only a minimum/maximum value is known

Is there a branch of statistics that deals with data for which exact values are not known, but for each individual, we know either a maximum or minimum bound to the value? I suspect that my problem ...
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15 views

Precision adjustment in biomarker analyses

In a causal modeling framework, we are concerned with measuring an association between an exposure and an outcome. To do that, we usually fit a regression model for the outcome as the "y" on the ...
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1answer
31 views

Fisher's exact test in RNA-Seq

In RNA-Seq analysis it is common to use tests analogous to Fisher's exact test to evaluate whether a gene is differentially expressed in two measured conditions. Fisher's exact test relies on ...
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17 views

Combining FDR value acquired from different microarray probes

Dear all great helpers, First of all, I would like to note that I'm quite new in Microarray analysis, and I hope you all be patient with me. I would like to provide an example and ask you all a ...
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35 views

Probability applied to cellular research

My friend reached out to me with this question, which he says is a simplified version of a cellular array question he is stuck on for his chemical bio research (Masters program). I have a grid of 10 ...
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1answer
25 views

Analysing the order of arrivals using a permutation test

I have data on the arrival times of bird species to bird feeders. I'm interested in asking the question 'does species identity affect arrival order' In R my data look something like this: ...
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1answer
47 views

How to analyse animal arrival times to food

I have created spatial foraging models with populations of 5 animal species that search for food. Each model allows to species to vary in certain parameters e.g. speed. And each model run has ...
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11 views

How do I combine and analyse data from a repeated assay?

I have 3 treatment groups (Con, T1, T2) which contain 6 mice each and have run an assay to determine a specific enzyme's activity. I've repeated the same assay for the entire cohort 4 times (on ...
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1answer
49 views

How to run Meta-analysis when data are given in OR and CI

I am currently working on my Master's Thesis (meta-analysis) and I have identified some articles with only OR given, so I have calculated the OR and CI for all of the articles to ensure they're in a ...
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1answer
26 views

Need help to simulate Survival Times with a time-varying Covariate

I would really appreciate if someone can help me figure this out as I have been working on it for few days now and I don't know what I'm missing that it's not working. Basically, my goal is to sample ...
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1answer
17 views

How to get real value from log adjustement value

I am looking for some data for my research, and found reliable graph which showed the correlation of fetal weight and gestational age which is what I want. However, the weight in that scatter plot ...
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8 views

Can I conduct multilevel analysis with two aggregated data sources?

I have two data sources with completely different specific individuals. One contains individuals answering whether or not they have watched the movie "Lego", and the other date source contains ...
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1answer
44 views

How to calculate mutual information from frequencies

Can someone explain to me how to calculate mutual information from contingency table? I have a contingency table containing counts from a sample of data And I want to calculate the mutual ...
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1answer
37 views

Find a window of ‘best correlation’ – exploratory analysis

I have data from a neurobiological experiment and I'm interested in learning which parts of multiple time-series (e.g. event-related potentials) best explain behavioural data (e.g. accuracy). Rather ...
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2answers
77 views

Can I apply statistics to catch rare diseases or make decisions about fate?

Suppose I am 50 years old and a study found that in my city 10 people (CI=4 people) die at 50. Now it's July and I have a very malignant disseminated cancer and this year 14 people died at age 50 in ...
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12 views

Hypothesis test design taking into account follow-up segmentation studies

Suppose I want to have a simple test with one treatment group and one control group. Let's assume the treatment for the treatment group is increasing a quantity $X$ by $10\%$. I have two questions: ...
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16 views

Are there any statistical fallacies that go with E-values?

I am presently learning how to use bioinformatics tools and among the first things to encounter was the notion of an E-value, explained on NCBI's help page for sequence alignment tool BLAST. As far as ...
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1answer
56 views

Bayesian biostatistics book

I am looking for a good book on biostatistics from a Bayesian point of view. I am going to be starting some research in oncology and so books geared towards that would be great, but also just a ...
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2answers
38 views

Which statistical test is appropriate for my data?

First 5 rows of my data are as follows: ...
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1answer
28 views

Is it possible to apply PCA to the reconstructed data of ICA?

I have read that it is not possible to verify the variance and order of independent component extracted from ICA. So, I reconstructed the spectra from matrix A and ST(independent component) then ...
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1answer
56 views

Can ANCOVA be used with a dichotomous dependent variable? If not, what have these authors done?

As stated above, if and how can ANCOVA be used with a dichotomous variable as the dependent/outcome variable? I found an article of which I wish to replicate some analyses ...
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17 views

How to calculate a score system

How can i create a scoring system using different variables (like score used in medicine)? I can calculate a regression equation but i'm having trouble converting this equation to a score assigning ...
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15 views

Prediction of one outcome using another

I have a general question. Suppose I have fit two separate longitudinal mixed effects models (say, model A and model B), they can both be simple and contain only time as a covariate. Say I have ...
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35 views

What is the impact of model accuracy on the reliability of random forest variable importance?

Just for some context, I'm asking this question from a biostastics perspective. Say you have gene expression data from multiple samples that fall under class A or class B. You then choose to build a ...
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Biasing regression by repeating variables

I'm building linear discrimination analyses and logistic regressions and I am trying to bias the regressions to favor specific variables. Each variable represents chemical information from a specific ...
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22 views

What kind of methods do I need to use in order to analyze this kind of health dataset

I've recently been given a dataset with the following variables: -BMI -Type of Therapy (indicated by 1, 2, or 3) -ADH Levels -HIV positive or negative (0,1 dummy variables) -Systolic blood pressure ...
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30 views

Statistical Analysis with repeated measures categorical data

For my Master thesis I looked at behavioral responses of fish by quantifying their position as a reaction to a certain treatment. I have 20 Fish that I measured on 7 consecutive days. Every day, each ...
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8 views

Power Calculation for Gene Significance

So, I think I need to do a power calculation for the following, but I am really not sure if that's the right procedure to use: I am looking at gene types in cancer, and I want to figure out if ...
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1answer
87 views

How to become a biostatistician? [closed]

What should a graduate student (MS in biostat) to be prepared to become a biostatistician? I've learn some statistics. But what I do now is just like statistician. I am just wondering what I should ...
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11 views

Pair-wise analysis with large amounts of data

I was asked to do a pair-wise analysis with target genes(~60) vs. a large amount of expressed genes (~4200). Can anyone shed some light onto what the most efficent way to do this is? I was going to ...
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1answer
35 views

What does 'Quantile Distribution' exactly refer to?

I am reading an article about normalization of next-generation sequencing (NGS) data (e.g. RNA-seq) where they use the notion of 'quantile distribution' (page 2). However, being a novice in the realm ...
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16 views

Is t-student enough for comparing these?

I'd like to compare two methods of measuring compounds quantity on chromatography paper, which we may call method A and method B (kind of like counting the same things using two different machines). ...
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40 views

In medical statistics, what is usually meant by “internal precision”?

I have come across the term "internal precision" in some books and papers and was wondering what this usually would refer to. Is there a standard definition for this term? Thanks!
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34 views

Comparing across groups and classifying (as in DFA) with non-normal data

I study birdsong, and am examining the structural song differences across multiple geographic groups (101 individuals across 3 groups), as measured via ~20 structure-related variables. I had hoped to ...
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Why using volcano plots in biostatistics?

In biology, it seems common to use a "volcano plot". Typically, it displays $-log_{10}(\text{p-value})$ in function of the fold-change (=difference of means between two biological conditions). See for ...