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Forum: Biostatistics

Epidemiology and biostatistics, public health research. GLM, logistic regression, survival analysis, clinical trials.

  1. Meta-analysis of cross-sectional studies with both one and two study groups

    Hello, I have a question about a meta-analysis I would like to run, comparing outcome measure Y in 'patients' groups (patients) and 'healthy'...

    Started by RutgerAussie‎, 06-15-2015 10:25 PM
    • Replies: 5
    • Views: 1,905
    06-17-2015, 02:21 AM Go to last post
  2. separate a population into groups using 3 sets of data at once

    Hi there, I'm working on a population for which I have done 3 chemical analyses that give the concentration of different products in their tissues....

    Started by guamfr‎, 06-10-2015 01:19 PM
    multiple datasets, sample groups
    • Replies: 2
    • Views: 1,163
    06-16-2015, 12:04 PM Go to last post
  3. Confidence interval for person time incidence rate

    Dear everyone, I would like to estimate a 95%CI of person time incidence rate (as 45 death per 10,000 person year) Anyone knows a way to estimate...

    Started by didye‎, 06-12-2015 03:45 AM
    confidence intervals, incidence rate, kaplan meier, person-time
    • Replies: 2
    • Views: 1,678
    06-15-2015, 02:41 PM Go to last post
  4. Correlating bird diversity with sampled parameters like area size, elevation R-studio

    For my thesis I need to find the connection between bird diversity and a bunch of parameters we recorded in the field for each locality. The recorded...

    Started by Hanneske4‎, 06-13-2015 05:41 AM
    • Replies: 0
    • Views: 1,394
    06-13-2015, 05:41 AM Go to last post
  5. Power and Sample Size Calculation

    Hi, First post here--i'm having trouble figuring out how to calculate the sample size for a study I'm planning. I don't have much statistics...

    Started by alumrock12‎, 06-10-2015 03:02 PM
    • Replies: 2
    • Views: 2,214
    06-12-2015, 07:28 PM Go to last post
  6. how to analyse 28 blood parameters in 3 stages of the disease ?

    hello, I would like to do an analysis of 28 blood parameters in 3 stages of the disease all parameters have specific numerical values I have...

    Started by bekble‎, 06-12-2015 05:02 PM
    • Replies: 0
    • Views: 1,115
    06-12-2015, 05:02 PM Go to last post
  7. Logistic Regression & Interaction Term

    Hi there, I'm trying to predict whether or not a patient has a simultaneous prescription order with various variables. To make it more clear... DV...

    Started by gene2420‎, 06-12-2015 01:38 PM
    • Replies: 6
    • Views: 1,885
    06-12-2015, 04:38 PM Go to last post
  8. No Wald Chi2 or Prob > Chi2 value generated for logistic regression?

    I am trying to run a logistic regression analysis using STATA and get the following output: Why is no value generated for my Wald Chi2 and Prob >...

    Started by PublicHealthGuy‎, 06-10-2015 09:54 AM
    • Replies: 3
    • Views: 2,581
    06-11-2015, 02:12 AM Go to last post
  9. How to incorporate data from a previous trial

    Can I incorporate data from a previous trial in a new trial without any adjustment for bias (individual subject data)? If not, which is the best...

    Started by estrucida‎, 06-10-2015 06:45 AM
    • Replies: 0
    • Views: 734
    06-10-2015, 06:45 AM Go to last post
  10. Power calculation

    I am working on a study that aims to assess predictors of insufficient food intake among elderly patients. In the study I am evaluating (9)...

    Started by Rouba‎, 06-09-2015 10:19 AM
    • Replies: 0
    • Views: 846
    06-09-2015, 10:19 AM Go to last post
  11. Incidence rate in a cohort with small sample size

    I have a small cohort of people with a specific disease (n=300) and studying the incidence of a related disease (which is kind of rare and normally...

    Started by Rerun‎, 06-08-2015 05:16 AM
    incidence rate, sample size, standardization
    • Replies: 5
    • Views: 1,704
    06-08-2015, 01:17 PM Go to last post
  12. Basic help with stats for drug treatments

    Hi there :wave: So I haven't a clue where to start and am hoping someone on here can point me in the right direction. I'm starting to analyse my...

    Started by CEJ‎, 06-08-2015 09:16 AM
    anova, basic, normal distribution, numerical, t test
    • Replies: 1
    • Views: 1,610
    06-08-2015, 11:06 AM Go to last post
  13. Removing Batch Effects (with svaseq and Combat)

    Hi everyone ! :) I'm a french student, so sorry in advance for my english... I'll try to do my best :). I currently work on a data set with a...

    Started by Vanille‎, 06-07-2015 02:48 AM
    • Replies: 0
    • Views: 2,968
    06-07-2015, 02:48 AM Go to last post
  14. Help with glm--- Simple Logistic Regression

    Hi All! Thanks for reading. I wanted to compare month of sample collection (April, May, June, and July) to presence/absence data (coded in binary...

    Started by ecologist‎, 06-06-2015 12:39 PM
    glm, logistic regression, r code, simple regression
    • Replies: 1
    • Views: 1,370
    06-06-2015, 01:25 PM Go to last post
  15. interpreting logistic regression in case p=0.0 and/or p=1.0

    Hi there, I have this (fake) example: case yes no a 25 1 b 30 0 c 0 20 I want to compare the percent of "yes" in the...

    Started by eric1708‎, 06-04-2015 04:23 AM
    • Replies: 0
    • Views: 1,095
    06-04-2015, 04:23 AM Go to last post
  16. KM curve

    Hi all, If I have a KM curve (survival vs years) and I have the number at risk each year (as well as hazard ratio for death over a median follow up...

    Started by ahmmri‎, 06-03-2015 06:20 PM
    • Replies: 3
    • Views: 2,171
    06-03-2015, 09:48 PM Go to last post
  17. Presence/absence multivariate data

    Hi, I'm trying to analyse some data I've gathered from some fossils. I have about 40 different specimens and for each specimen I've recorded the...

    Started by RaskellVirmoors‎, 06-03-2015 12:54 PM
    • Replies: 0
    • Views: 3,892
    06-03-2015, 12:54 PM Go to last post
  18. help with comparing paired values

    Hi I have a question regarding comparing data. I have data in spss as presented here:...the list goes on for a thousand entries (ie...A, B, C, D,...

    Started by spaceprobe‎, 06-01-2015 05:01 PM
    • Replies: 2
    • Views: 1,781
    06-02-2015, 03:55 PM Go to last post
  19. Comparing categorical outcome variables in repeated measures design

    I am working on an observational prospective longitudinal study with a repeated measures design. The same categorical outcome is measured for five...

    Started by AlexLev‎, 06-02-2015 03:19 PM
    categorical variables, missing data, multivariate analysis, repeated measure, repeated measurements
    • Replies: 0
    • Views: 1,369
    06-02-2015, 03:19 PM Go to last post
  20. Comparing proportion between categorical outcome variables, repeated measures design

    I am working on an observational prospective longitudinal study with a repeated measures design. The same categorical outcome is measured for five...

    Started by AlexLev‎, 06-02-2015 03:15 PM
    categorical variables, missing data, multivariate analysis, repeated measure, repeated measurement
    • Replies: 0
    • Views: 1,145
    06-02-2015, 03:15 PM Go to last post
  21. 2-way ANOVA on non-normal, hetergeneous data

    I'm trying to analyze growth data from chicks, and I need to perform the equivalent of a 2-way ANOVA (2x2 design, unequal sample sizes), but my data...

    Started by mogetons‎, 05-23-2011 06:59 PM
    • Replies: 8
    • Views: 29,195
    06-01-2015, 05:19 AM Go to last post
  22. Question How do we avoid pseudoreplication while examining stickleback-gender in perch stomach

    We are working on a project were the sex of sticklebacks in perch stomachs are assesed. The question here is; how do we avoid pseudoreplication? We...

    Started by mr_blueberry‎, 05-29-2015 06:15 AM
    chi square, pseudoreplication, t-test
    • Replies: 0
    • Views: 1,632
    05-29-2015, 06:15 AM Go to last post
  23. Probability of association in binary variables (allergy dataset)

    Hi I am an MD analyzing a series of patients who have undergone allergy testing. For each patient (20000 in total), there are 40 tested allergens...

    Started by Mdl4487‎, 05-24-2015 03:25 PM
    • Replies: 1
    • Views: 1,790
    05-26-2015, 06:17 AM Go to last post
  24. Dealing with multiple confounding variables

    for example, we have 3 confounding random variables, x1, x2 and x3 with 3 different variances. If we had to treat each variable alone, we would have...

    Started by isaacadel‎, 05-20-2015 10:28 PM
    • Replies: 3
    • Views: 1,651
    05-24-2015, 06:24 AM Go to last post
  25. logistic regression versus PCA

    I am doing a retrospective research on breast cancer using multivariate estimates. The aim of the research is to calculate the probability of finding...

    Started by isaacadel‎, 05-20-2015 08:52 PM
    • Replies: 0
    • Views: 1,669
    05-20-2015, 08:52 PM Go to last post
  26. Adjustment for Odds Ratios

    At present, I am working on a meta-analysis that observes the effect of physical activity for a disease (i.e. cancer). For each study we have used...

    Started by jle‎, 05-13-2015 06:24 PM
    • Replies: 10
    • Views: 2,031
    05-17-2015, 09:31 PM Go to last post
  27. Normal versus non-normal - presentation of results in publication

    Dear all Can anyone help me with the following question: I have a outcome variable that is compared for different grouping variables. For some of...

    Started by sternchen‎, 05-14-2015 04:48 AM
    • Replies: 3
    • Views: 862
    05-14-2015, 08:49 AM Go to last post
  28. Adjustment for confounders for testing equality of variance

    Dear all I wonder if there is a method that allows to adjust for confounding variables when testing for the equality of variances. I am comparing...

    Started by sternchen‎, 05-14-2015 05:06 AM
    • Replies: 1
    • Views: 1,162
    05-14-2015, 05:33 AM Go to last post
  29. Kruskall-Wallis/Dunn or Mann-Whitney to compare communities along an area?

    Hi, I would like to know your opinion about the best statistical approach to use in the following case: - 10 sampling points distributed along an...

    Started by GSousa‎, 05-12-2015 04:34 AM
    • Replies: 0
    • Views: 984
    05-12-2015, 04:34 AM Go to last post
  30. Smile Comparing groups/sites---need advice identifying variables and appropriate tests

    Hi, thank you for reading this and your potential input. This is a research study. I examined the prevalence of parasites in one insect species...

    Started by ecologist‎, 05-11-2015 03:54 PM
    chi square test, fisher's exact test, glmm, logistic regression
    • Replies: 0
    • Views: 945
    05-11-2015, 03:54 PM Go to last post
  31. Paired or unpaired data and questions about test with >2 groups

    Hi guys! I am here for some help with my statistics. I am currently working on a small project involving the expression of surface markers on cells...

    Started by Ilarja‎, 05-06-2015 03:18 AM
    mann whitney u test, paired data
    • Replies: 2
    • Views: 1,104
    05-10-2015, 04:15 PM Go to last post
  32. Wilcoxon test for statistical significance

    Hi guys, I have a simple question (sry for the probably imprecise formulation, I never went to a statistics class) Assume we have a population...

    Started by Stats_Newbie‎, 05-04-2015 03:15 PM
    • Replies: 5
    • Views: 1,429
    05-05-2015, 04:23 PM Go to last post
  33. Goodness of Fit of Time Series Prediction

    I am an academic neuroscientist working on the following project: I am attempting to determine the evoked response of a sensory nerve (time series in...

    Started by AngryWaffles‎, 05-05-2015 10:07 AM
    • Replies: 0
    • Views: 1,168
    05-05-2015, 10:07 AM Go to last post
  34. Significance testing among groups of time series data

    I have produced 2 groups of time series data. Each group contains 100 time series, each of which is a solution to an ordinary differential equation...

    Started by ELMC‎, 11-01-2014 12:26 PM
    • Replies: 1
    • Views: 1,641
    05-05-2015, 09:39 AM Go to last post
  35. Comparing Treatments for Spinal Cord Injury

    Hi Guys. First post in this forum (actually, in any statistics forum). I am not from an English speaking country, so you may find some grammatical...

    Started by LucasConzatti‎, 05-03-2015 05:33 PM
    anova, repeated measure anova
    • Replies: 4
    • Views: 1,469
    05-04-2015, 09:26 AM Go to last post
  36. ROC curve after logistic

    Hello all. I have a dataset of around 700 subjects. I wanted to test whether the blood values of a protein are associated to a certain disease and...

    Started by Ralph84‎, 05-03-2015 10:56 AM
    • Replies: 1
    • Views: 919
    05-03-2015, 01:05 PM Go to last post
  37. Making sense of the directionality parameter

    Hello, This post has been cross-posted here. I fail to delete the current post to leave only the other post open. Feel free to delete this post if...

    Started by Remi‎, 05-03-2015 11:52 AM
    articles, dispersion parameter, intuition, logistic regression
    • Replies: 0
    • Views: 1,363
    05-03-2015, 11:52 AM Go to last post
  38. Comparing the Power and Effect Size from Different Studies

    Hi there Talk Stats Community, I am an undergraduate research assistant. Currently I am doing research on a project, and our results have...

    Started by mtm3123‎, 05-02-2015 12:21 AM
    comparison, effect size, power
    • Replies: 0
    • Views: 1,355
    05-02-2015, 12:21 AM Go to last post
  39. Advice on appropriate test on proportions with three factors with replication

    I am planning a study with three factors (salinity, parasite type and species). Can anyone suggest an appropriate statistical test? I am wondering if...

    Started by luhar‎, 05-01-2015 02:00 PM
    • Replies: 0
    • Views: 1,576
    05-01-2015, 02:00 PM Go to last post
  40. Calculate Incidence rate for disease with fertility/mortality data

    I am trying to calculate disease incidence in a certain country. I have the number of cases detected over 10 year period. The disease affects...

    Started by notimer‎, 04-28-2015 03:38 PM
    biostatistics, incidence rate, population statistics
    • Replies: 2
    • Views: 1,534
    05-01-2015, 12:29 PM Go to last post
  41. Transforming interaction coefficients in odds ratio (logistic regression)

    Hello everyone. :wave: First of all, sorry for my english, I am not english mother tongue. Second, sorry for my stats knowledge, I'm not a...

    Started by silviezza‎, 04-29-2015 11:28 AM
    • Replies: 2
    • Views: 1,539
    04-30-2015, 08:09 AM Go to last post
  42. One sample study design - Multivariate methods?

    Good Day, I am planning a one sample study of 230 patients. I am thinking of using the one sample t-test and the binomial test to perform...

    Started by tyronm20‎, 04-25-2015 09:47 AM
    • Replies: 5
    • Views: 1,666
    04-28-2015, 01:15 PM Go to last post
  43. How to compare samples of different sizes to look for a correlation

    Hello :) I'm hoping to find somebody that can give me some advice with my Statistics. I carried out a study on birds diet. My results show...

    Started by Alycw‎, 04-26-2015 03:54 PM
    • Replies: 0
    • Views: 1,032
    04-26-2015, 03:54 PM Go to last post
  44. How to estimate transition probabilities in the absence of individual patient data?

    What I tried so far is to read of the survival curves given in clinical trials with Plot Digitizer, with months ((t)months) as the X axis and...

    Started by iknownothing‎, 04-25-2015 11:22 AM
    • Replies: 0
    • Views: 1,178
    04-25-2015, 11:22 AM Go to last post
  45. Dunn's Multiple Comparison Test - Graphpad

    Hey, So I worked with non-parametric data (more than 3 groups) so I did the Kruskal-Wallis test to compare these groups. To see which group...

    Started by biomed‎, 04-25-2015 03:37 AM
    • Replies: 0
    • Views: 2,139
    04-25-2015, 03:37 AM Go to last post
  46. Average individual correlations or perform 1 set of correlations

    First of all thanks for your time reading this post. I got some issue with correlation analysis that I am not able to solve at all as for more...

    Started by aloik‎, 04-24-2015 07:44 AM
    • Replies: 0
    • Views: 856
    04-24-2015, 07:44 AM Go to last post
  47. biological relevance of low fold changes in gene/protein expression?

    Hello, I have proteomic data pertaining to organs of rats treated chronically with a low dose of a chemical. The rats have developed pathologies...

    Started by VladimirM‎, 04-22-2015 11:21 AM
    • Replies: 0
    • Views: 1,228
    04-22-2015, 11:21 AM Go to last post
  48. Spearmans Correlation Doubt

    Hello! I have some doubts about Spearmans's Correlation and I would like to ask your help! I have 5 variables (3 independent and 2 dependent) and...

    Started by pedro90‎, 04-16-2015 05:30 AM
    • Replies: 1
    • Views: 1,608
    04-17-2015, 03:44 PM Go to last post
  49. Can subject be a factor?

    Let's say we have an epidemiology research with 5 subjects (for simplicity): John, Mike, Andy, Frank and Philip. They contacted meningitis and their...

    Started by nick01‎, 04-15-2015 10:09 AM
    error term, two-way anova, zero degrees of freedom
    • Replies: 2
    • Views: 1,166
    04-15-2015, 11:52 AM Go to last post
  50. what to do with duplicate subjects in data set

    I have 2 subjects in my data set that I suspect are duplicates-also the data is highly unusual, do I exclude then from analysis? According to the...

    Started by darcymagoo@yahoo.com‎, 04-12-2015 04:32 PM
    • Replies: 1
    • Views: 1,532
    04-12-2015, 08:53 PM Go to last post
  51. pairwise associations-which model to run?

    Should I perform multiple linear regression for the following homework question? Perform the necessary analyses for creating “Table Q1: Pairwise...

    Started by darcymagoo@yahoo.com‎, 04-12-2015 04:29 PM
    • Replies: 0
    • Views: 1,183
    04-12-2015, 04:29 PM Go to last post
  52. Question weighting of aligned subsequences by their length

    I have a pool of subsequences, each one associated with a probability (and other properties that you don't need to know) that quantifies how...

    Started by tevang‎, 04-11-2015 10:13 AM
    alignment, probability, sequence, weighting
    • Replies: 0
    • Views: 1,108
    04-11-2015, 10:13 AM Go to last post
  53. Taking the Mean of a Mean

    Hello, I have 2 groups, each with 3 subjects and each subject with 5 replicate values. I want to compare the means of the measured values between...

    Started by Universal Exports‎, 04-10-2015 11:28 AM
    • Replies: 0
    • Views: 1,456
    04-10-2015, 11:28 AM Go to last post
  54. How to format a null hypothesis without statistical analysis

    I had to complete a research project that involved a cell membrane protein, and I had to find if there was a correlation to its presence on cells and...

    Started by Orange91‎, 04-09-2015 12:35 PM
    • Replies: 1
    • Views: 1,165
    04-09-2015, 01:34 PM Go to last post
  55. How to compare IRRs of two different groups?

    Hello all, thanks in advance for your help. This is my question: I have a structured panel data for repeated measure over time per single person ...

    Started by Ralph84‎, 04-09-2015 08:54 AM
    • Replies: 3
    • Views: 2,268
    04-09-2015, 11:45 AM Go to last post
  56. How to analyze my longitudinal data

    Hi all, I've been struggling to figure out the best way to analyze my data. I randomized participants to one of 3 groups and had them complete my...

    Started by capobl‎, 04-08-2015 10:32 AM
    • Replies: 2
    • Views: 1,420
    04-08-2015, 01:58 PM Go to last post
  57. Question Cox regression application in business/finance

    Hi all, I hope this is the right forum to ask as cox regression is usually use by bio-statisticians. My research is about companies which...

    Started by roslina‎, 04-07-2015 11:10 AM
    cox regression, spss, time dependent
    • Replies: 4
    • Views: 2,936
    04-07-2015, 10:29 PM Go to last post
  58. sample size recalculation mid-trial based on unplanned look at data

    what is the current thinking on sample size recalculation mid-trial based on unplanned look at the data. suspect futility and want to either stop...

    Started by msecic‎, 08-28-2014 12:52 PM
    • Replies: 1
    • Views: 1,542
    04-07-2015, 10:12 AM Go to last post
  59. Canonical Correspondance Analysis interpretation

    Hi , I'm trying to do a CCA on two data sets , species dataset vs environment variables dataset the results are in the attached png . ...

    Started by chmilblik‎, 04-05-2015 10:05 AM
    • Replies: 1
    • Views: 2,105
    04-05-2015, 11:13 AM Go to last post
  60. Multiple imputation and ROC curve anlaysis

    Hi, I have searched extensively for a solution to the following problem, without success. I have used multiple imputation on SPSS 22 to create 5...

    Started by CE479‎, 03-31-2015 04:25 PM
    • Replies: 9
    • Views: 8,830
    04-02-2015, 12:36 PM Go to last post

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