Tagged Questions

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

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0answers
18 views

Parametric test [closed]

Which of the following parametric tests is an analog of the Chi Square goodness of fit test? Answer ANOVA Wilcoxon matched-pairs test Pearson's correlation coefficient None of the above
0
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0answers
22 views

Difference in Difference

How to interpret parameter of difference in difference with respect to public health ? Students had taken special care from 2010(baseline) to 2011(follow-up)period. say, in regression approach ...
0
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0answers
11 views

Modeling Switch-Like vs Continuous Signal

I'm currently trying to figure out the best way to model a given scenario, but am unsure of the best way to go about it, so I'll explain the situation in as much detail as possible. So I work in a ...
0
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0answers
11 views

selecting genes specific/agnostic to condition

I have a microarray transcriptomics experiment. The design of which is something like this : ...
0
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2answers
89 views

Machine Learning and Biostatistics [closed]

I am interested in a few areas with biostatistics, and was reading the course catalog at a university that offers machine learning. I am taking topology now, and i think machine learning uses ...
0
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0answers
15 views

Test(s) For Comparing qPCR results / ΔΔCт values

To be clear, I'm talking about real-time polmerase chain reaction (qPCR), not Principle Component Regression. Though from a company selling qPCR reagents, here is a good walk-through of the ...
0
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0answers
20 views

What books to read for Biostatistician position supporting product develpment for in -vitro diagnostics?

This is not a question concerning a specific statistical method, but I need an advice. I am interested in a position as a biostatistician to support product development for in-vitro diagnostics. I ...
0
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0answers
30 views

Testing of sensitivity for different algorithms

I have some queries I would like to discuss, I am doing some analysis for sensitivity. I am not from the field of statistics. I work with RNA-Seq data. The thing is I have found some genes which are ...
0
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0answers
5 views

Controllong random deviation

I have a process in which X is a molecule going through birth ($x \rightarrow x + 1$) and death $(x \rightarrow x - 1)$. Rate of both reactions, namely synthesis rate for birth and elimination rate ...
1
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1answer
80 views

Bayesian inference of a clinical trial for clinicians

I am a clinician who is more adept than average at interpreting clinical trials in a frequentist manner. At this point, interpreting a trial as a frequentist has kind of become a procedure: check ...
0
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0answers
12 views

Heterozygosity and the Wright-Fisher model

I was reading the textbook [Probability Models for DNA Sequence Evolution][1] by Durrett. In chapter 1, he discusses the Wright ...
2
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3answers
101 views

Beyond the basics: intermediate medical statistics textbooks suggestions

I am a soon-to-be physician. During my studies I have taken a class in biostatistics. I own Martin Bland's "An introduction to medical statistics", which was a required textbooks at the time, and ...
2
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1answer
33 views

wilcox.test usage in R

I would like to know if there is a difference in the values taken from measurements of a given characteristic sampled at primary forest (Point=1) and secondary ...
4
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1answer
83 views

Does an exponential model fit my data?

I am measuring accumulation of a fluorescent-tagged protein at a particular location within a cell over time. In previous experiments that I have performed, I see a standard exponential distribution ...
3
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1answer
53 views

Identifying the experimental unit

I have included a diagram of an experiment where cells are pooled from multiple animals, cells from the pool are then allocated to different treatments and a measurement is taken from each individual ...
2
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1answer
73 views

Standard Deviation After Subtracting One Mean From Another

I've got two sets of data from some fluorescent cells. The first set is when the cells don't have their fluorescence switched on, but they are still faintly glowing. The second set is when they do ...
0
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2answers
23 views

Interaction between variables

I would like to regress basal metabolic rate (BMR) on height, weight, age and gender. How do I do this taking into consideration the interaction between the variable? Wouldn't I have to consider ...
2
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2answers
61 views

Best distribution to handle a ratio of counts as a response variable

A quick statistics question (apologies for the added biology): I have two sets of counts (for the expression of two different isoforms of a particular gene), and to generate the response variable in ...
0
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0answers
22 views

Two way ANOVA or ANCOVA

I need to show that BMI of adults is neither age nor gender specific. Should I do ANCOVA or randomly make age groups and do two way ANOVA?
0
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0answers
31 views

Beyond multiple linear regression for longitudinal data?

I have a relatively large dataset from a longitudinal study (~100k subjects and ~10 random effects) where the outcome is a real-valued parameter. A simple run of R's ...
0
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0answers
22 views

minimum abundance of a bacterial species

I conducted a study in which I used sequencing of marker genes to study bacterial diversity and I would like to calculate the minimum abundance for a species to still be detected. The total volume ...
2
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1answer
42 views

How to measure the magnitude of difference between two gaussian distributions? Specifically with rates of DNA mutations

As the title says I want to quantify the difference in the rates of sequence change between genes. When I measure the mutation rates between my subgenomes I can determine a significant but slight ...
1
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1answer
148 views

Two-way MANOVA vs. two-way ANOVA on a composite variable

Is using a 2 way MANOVA to check whether height and weight differ across age groups and gender, the same as using a 2 way ANOVA to check whether BMI (wt in kg/ht in m$^2$) differ across age groups and ...
1
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0answers
58 views

Using repeated measures anova: Am I right?

We have just finished an experiment, where we had samples distributed into 6 groups and each group receiving a different treatment. Each group had 5 samples, with 20 replicate measurements taken per ...
1
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0answers
23 views

Type-1 Error of the Two-Stage Design

Background on Two-Stage Designs In clinical trials, we are often interested in the response rate $p$ for an experimental treatment. In a typical trial, we might expose $n$ patients to the treatment ...
1
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1answer
51 views

How to calculate degrees of freedom for chi squared test

I am very new to stats, and if the chi squared test is not the best way to handle this, please let me know. To simplify what I'm trying to do, I have many separate lists of genes. Each list is a ...
0
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1answer
53 views

How do I calculate the p-value in a gene enrichment analysis, using parametric and non-parametric methods?

I have a list of 20 QTL from an experiment involving a certain phenotype related to bone development. Of all the candidate genes within the 20 QTL intervals, 5 are associated with a certain disease ...
2
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1answer
55 views

statistical analysis of events in a given time interval

I am attempting to analyze biological data, to see whether the number of events in a given time interval is more/less than expected based on the overall frequency. How would one approach this? An ...
1
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1answer
4k views

Correlations between continuous and categorical (nominal) variables

I would like to find the correlation between a continuous (dependent variable) and a categorical (nominal: gender, independent variable) variable. Continuous data is not normally distributed. Before, ...
1
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0answers
53 views

How to perform statistical test for enrichment of gene lists?

In a typical ChIP-Seq experiment, we found a transcription factor ABC peaks on 590 genes. 242 genes out of the 590 genes are classified as ...
1
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0answers
16 views

Prioritization based on three factors

Background: Sales reps visit doctor and detail about a product/drug. One visit is termed as one call. In return he writes the prescriptions to doctors prescribing that particular drug. Problem ...
0
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1answer
41 views

Which statistics to use?

I have a medical research in which I have two sets of data Control group: People who have no ailment. Study group: People who have some particular ailment. Within each category there are ...
2
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0answers
58 views

Poisson regression in R glm(): concept and practice

I have a dataset data about a group of persons developing events with Poisson distribution. These events are uniform and can be recurrent in some of the subjects. ...
1
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1answer
40 views

Calculating variance for microarray data?

I have microarray data in which there are three biological replicates for each of the conditions. I am interested in a numerical estimate of how well the replicates correspond with one another, so I ...
0
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0answers
89 views

Inferring the statistical tests performed in a paper

I am in great need of help in order to infer the statistical hypothesis tests performed in Xanthelasmata, arcus corneae, and ischaemic vascular disease and death in general population: prospective ...
1
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0answers
13 views

Statistical technique to assess nutrition

My goal is to find risk factors for a disease. I think that a malnutrition is a risk factor for this disease. I have 5 variables that indicate the frequencies of ...
2
votes
1answer
71 views

Statistical paired test for relative change

Do you have any suggestions, which test I should use in order check if the relative change is statistically different than 0. I am sure that I should check the relative (fold) changes. Specifically, ...
0
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1answer
197 views

What is a tertile average of a group?

I came across a paper , where they have taken tertile average of a hormone level in a group. I am wondering what difference does calculating tertile average make? Thank You!
1
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1answer
49 views

Needing help in order to infer the statistical hypothesis tests performed in an old paper

I am in great need of help in order to infer the statistical hypothesis tests performed in an old paper. However I need to make some reasonable guesses only from the abstract of the paper since the ...
0
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0answers
30 views

What are the data needed to conduct Cost-Effectiveness Analysis?

I'm aiming to conduct a cost-effectiveness analysis (CEA) of the introduction of a new vaccine for HPV (Human Papillomavirus), in a developing country ( I think this will be done from the societal ...
1
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1answer
88 views

Quantifying applicability domain for predictive models?

I have a big dataset and I want to build a classification model (svm, rf, ann etc.). Then I split the original dataset into training set and test set. I build the model using training set. After it ...
1
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1answer
50 views

Programs and procedure for Blackwood test?

I am looking for programs and procedure for the Bradley-Blackwood test, which is normally used to assess test-retest reproducibility.
0
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0answers
39 views

Training models for classification using different negative datasets

I'm working on a massively unbalanced binary classification task - Classification of given protein sequences as belonging to a certain (very small) class, or not. There are about 1,300 positive ...
0
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1answer
58 views

Any known example of research project being led by statistician in public health

(I am fully aware that my topic may not be relevant here, do let me know if this is true.) I am a research staff with training in epidemiology and biostatistics, working in government organization on ...
1
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0answers
46 views

Good reference book for statistics in medicine

I am looking for a good reference book for applying statistics to medical problems. I am interested in a practical book that describes concepts including statistical power, tests for comparing ...
0
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1answer
59 views

A Conditional Probability Problem

This is a biological problem, however the problem requires a statistical solution, so therefore I'll keep it as abstract as possible in order for statisticians to be also able to contemplate it - I'm ...
0
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1answer
56 views

which statistical test to use to compare 3 different types of regions? [duplicate]

I want to compare the percentage of a species in 3 different types of regions. Which statistical test should I use??
1
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0answers
73 views

Testing for significant difference in mortality rate between multiple groups

How do I test for a significant difference between the mortality rate of 4 groups (each group with a different n) group 1: mortality rate = 30.9%, n=55 group 2: mr = 0%, n = 4 group 3: mr = 23.3%, n ...
1
vote
1answer
26 views

Creating a translated sample by subtracting mode

Consider a sample $x_1,...,x_n$ which we will call the original sample. To create a translated sample $x_1+c,...,x_n+c$, we add a constant $c$ to each sample point. Let $y_i=x_i+c, ...
0
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0answers
34 views

Project in Bayesian biometrics

I'm working on a project about specific bird species on an island in the Northern Atlantic sea. The data seem reliable and pretty detailed, and range from the 18th century, however their structure and ...