biostatistics

  1. R

    Survival analysis at few dates: glms? logrank? cox ?

    Hello, In many documentation I have read that Kaplan-Meier curves followed by logrank test and/or cox models are the most recommended statistical methods to analyse Survival and test for different factors that may impact the Survival. However, I have also heard that these are suitable if I...
  2. O

    Power analysis

    Dear all, First of all I would like to thank you for helping me with this question. For my research I investigated 23 patients. I looked at there range of motion of the shoulder and investigated the angle at which a dislocation/relocation occurred during forward flexion (FF) and abduction...
  3. E

    Book Review - Essentials of Bio statistics: An overview with the help of software

    Would like to receive the review for the following book Essentials of Bio-statistics: An overview with the help of software www.ijsmi.com/book.php This book intends to provide an overview of biostatistics concepts and methodology through the use of statistical software. It helps clinicians...
  4. S

    Best statistical method for CFU/ml?

    I have sets of data in CFU/ml for different sampling sites collected in two different seasons. 1. How do I compare the CFU/ml between sampling sites within one season? 2. How do I compare the CFU/ml in different seasons of the same sampling site? one-way ANOVA?
  5. A

    Regression Analysis - Beta Values

    I have a question on a sample test for my upcoming prelims and I am unsure how to answer a question, scenario and questions below... A study measured dental measurements from the center of the pituitary to the pterygomaxillary fissure (measured in mm) for 11 girls and 16 boys at ages 8, 10, 12...
  6. W

    Statistical Tools for Analysis of Effect of Light, Temp, CO2, and pH on Growth Rate

    My question is, what may be the ideal tools to analyze the data from this experiment and what are some resources you can recommend to learn about them (textbooks, website, etc.). I'm also just starting to learn R so feel free to work that in there. I'm designing undergraduate research to be...
  7. R

    Problem with normalization and - proteomics analysis (LC-MS)

    Hi folks, I am working with proteomics data, containing mainly LC-MS and NMRI analysis. Firstly, I must normalise data to give valuable compound for biostatistics analysis such as data imputation. I have never had to deal with such data. Can you advise me on which method to choose (I usually...
  8. R

    reference interval determination

    Hi all, I was wondering if I could ask for some help from some more statistically inclined persons than myself. We are trying to determine a reference interval for a new machine that measures a particular protein in the blood of horses. This machine has never been used before in horses...
  9. R

    interpretation of a negative risk difference

    Hi, I am reviewing a cohort study and trying to make sense of the results. When considering mortality they presented their results as a risk difference which is a little different to what I normally see. Usually reported is RR or OR. In this case the results give a negative number. -35% (95%CI...
  10. U

    Rewriting integration by summation

    Suppose that n individuals have lifetimes represented by random variables T_1, T_2, \ldots, T_n. Instead of the observed values for each lifetime, we have a time t_i' which we know is either the lifetime or censoring time. Let us define a variable \delta_i=I(T_i=t_i') that equals 1 if...
  11. M

    efficient R code

    I have the following code in R to creat .ped file and .map file that is used in Plink "open-source whole genome association analysis toolset" I need more efficient R code since the data I have is 905460 rows and 1120 columns and it takes forever to run , " I didn't get results for 2 days...
  12. M

    Question on Odds ratio

    Hi, I have a basic understanding of odds ratio. I can't figure out how to integrate the space S into my odds ratio equation. For the following figure: S has 23000 genes, (all genes) A has 751 genes and (condition1) B has 375 genes (condition2) How do I calculate the OR for A ∩...
  13. N

    What distribution is better in these situations?

    I'm new in statistics and probability and I'm a little lost about what distribution is better in these situations: If a tumor is malignant or not --> Bernouilli Number of entries in an emergency service during a night, know that on average 20 entries are observed per night. --> Poisson Tumor...
  14. C

    Cox's regression

    Hello, I have some experimental data for animals with tumours. Unfortunately, they were not followed individually during a time course, but evaluated as groups. As a result, I have 6 predictors only for animals that have survived for each time point. I would like to test which of these...
  15. G

    Integrate different types of data from different studies?

    Hi, Is it possible to integrate different types of data from different studies? If yes, what precautions we must take? For example, let us assume there are 3 research papers. Research paper 1 gives information about variable X Research paper 2 gives information about variable Y Research paper...
  16. B

    Non parametric multivariate analysis. maybe :(

    Hello to everyone, i need some help with my statistical analysis. I have two different pharmacokinetic parameters. They result from two different models applied on the same data. These data are baseline and follow up data of 20 subjects. To sum up, for each subject, i have 4 measures: - two...
  17. A

    estimate a range of measures

    Hello everyone, I am a statistics student, I'm studying for a project in my University. I have to analyze the data, I have available the measures in millimeters corrisponding two different types of objects, of course I have already done tests to groups such as t-test, actually these organized...
  18. K

    N of 1 study looking at complex phenotypes and SNPs

    Hi All, I have a complicated question and can't find a resource that answers it comprehensively. I'm designing a study looking for linkage between a complex phenotype; how people respond to various different topical treatments. This will not be published in a scientific journal so will be...
  19. C

    Study Design for assessing efficacy of New Clinical Sign

    Hi! I am looking for some guidance as to what statistical tests I would need to do to know the significance of a study. The situation is this: Disease in Question is Sinusitis Gold Standard for Diagnosis is CT, but is seldom done as not all cases require confirmation. Cost-effectiveness...
  20. J

    Statistics for regional disease risk factors

    Hi, I've data set collected from 700 sheep farms from 5 regions of England (north, south, East, West, Central). The aim is find out if climate variables (maximum temperature, minimum temperature, rainfall) are predictors for animal disease in the regions, so the outcome variable (y) = number of...