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Forum: Biostatistics

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

  1. Ecology : re-group samples based on distance measure

    Hello, Good morning TalkStat Forum, hedre is my question of the day :) I have an ecological matrix of samples (rows) X species abundance...

    Started by Koblenz‎, 06-28-2013 02:42 AM
    • Replies: 4
    • Views: 2,667
    07-02-2013, 07:13 AM Go to last post
  2. Choosing a sample size for a pilot study

    I am trying to figure out how to compute a sample size. Since this is a pilot scale study the results will likely not be definitive, but I want to...

    Started by hodag‎, 06-26-2013 03:32 PM
    2 Pages
    1 2
    • Replies: 18
    • Views: 10,026
    07-01-2013, 09:52 AM Go to last post
  3. comparing the frequency use of vocabulary between two sign languages

    I am comparing the vocabulary of two sign languages in two locations to see if the vocabulary use in statistically different between locations. The...

    Started by R.Johnson‎, 06-30-2013 09:09 PM
    chi square?, fisher's exact test?
    • Replies: 0
    • Views: 1,938
    06-30-2013, 09:09 PM Go to last post
  4. testing a prognostic score

    Hi, can anyone please help me? I have to see to how a prognostic score correlates with patients' evolution, and by that I mean: mortality, days of...

    Started by sprite‎, 06-28-2013 12:16 PM
    • Replies: 5
    • Views: 2,231
    06-30-2013, 08:12 PM Go to last post
  5. Question Comparing a continuous variable vs a continuous and a nominal

    Hi. I'm studying the effect of hummingbird feeders on the hummingbirds' pollinization function. We counted the amount of birds feeding on artificial...

    Started by Core_Number‎, 06-27-2013 12:26 PM
    block, continuous, hummingbirds, nominal
    • Replies: 0
    • Views: 1,412
    06-27-2013, 12:26 PM Go to last post
  6. PCA for identifying bacteria species & concentration

    Hi all, For an experiment I'm trying to see whether I can distinguish bacteria species and concentration using fluorescence, and I'm stuck on...

    Started by SvenvBins‎, 06-05-2013 01:58 PM
    • Replies: 3
    • Views: 3,306
    06-27-2013, 10:41 AM Go to last post
  7. Post area under the ROC curve for a cutoff point

    I kindly requested help about a study of mine concerning ROC curve analysis in medical diagnosis. I use R software programme to find optimal...

    Started by gunelpinar‎, 06-03-2013 06:12 AM
    auc, roc
    • Replies: 2
    • Views: 4,702
    06-26-2013, 02:36 AM Go to last post
  8. Significant differences in significant differances

    Hello forum Gurus, I have tried search for a problem similar to mine in these forum to no avail. So here goes. I have 4 groups (A,B,C,D)...

    Started by Grebo‎, 06-24-2013 04:25 PM
    • Replies: 3
    • Views: 1,821
    06-25-2013, 03:10 PM Go to last post
  9. Interrupted time series analysis with comparison group

    Hi, I was wondering if you could provide some guidance with regards to study design and the statistical analysis i should use for a pilot study we...

    Started by Mmir‎, 06-24-2013 06:29 PM
    • Replies: 0
    • Views: 2,951
    06-24-2013, 06:29 PM Go to last post
  10. "As treated" analysis, fixed cohort analysis, and NNH?

    I had a few questions in regards to this study: http://www.bmj.com/content/346/bmj.f880.pdf%2Bhtml They conducted an "as treated" analysis and...

    Started by Matt1147‎, 06-23-2013 09:50 PM
    • Replies: 0
    • Views: 2,745
    06-23-2013, 09:50 PM Go to last post
  11. Paired or Unpaired t Test

    Hi, I am working on a project in which we are comparing data about two groups of patients: the experimental group of 12 patients who received a...

    Started by vigneshr11‎, 06-22-2013 04:07 PM
    paired or unpaired t test
    • Replies: 2
    • Views: 2,723
    06-22-2013, 09:07 PM Go to last post
  12. Which programming language/database to learn?

    I'm interested in pursuing a career in biostatistics, and I'm wondering which language/database will be useful in the field of...

    Started by randomcat‎, 06-20-2013 10:54 PM
    biostatistics, programming
    • Replies: 0
    • Views: 1,545
    06-20-2013, 10:54 PM Go to last post
  13. Appropriate tests for experimental crab growth and survival research

    Hi, I would like to know which test(s) would be most appropriate to analyze my data. I conducted an experiment with crabs to assess the effects...

    Started by Raphaelle‎, 06-20-2013 02:24 PM
    • Replies: 1
    • Views: 1,343
    06-20-2013, 03:18 PM Go to last post
  14. GLMM Predictor variables

    Hi all, I have a quick question regarding predictor variables in a GLMM analysis, a subject I am new to. I am running a study investigating...

    Started by bsr505‎, 06-20-2013 05:31 AM
    glmm, predictor, variables
    • Replies: 0
    • Views: 1,285
    06-20-2013, 05:31 AM Go to last post
  15. Accounting for demographics when outcome is rates

    Hello, I've been reading some public health papers and they account for demographic factors such as age, gender, and race in regression models...

    Started by phbios321‎, 06-13-2013 11:33 AM
    adjustment, crude rates, demographics, poisson regression
    • Replies: 7
    • Views: 2,176
    06-19-2013, 03:15 PM Go to last post
  16. Question Calculating effect size for a within group comparison of score before&after treatment

    Hi all, :wave: I am wondering which formula will be more suitable for calculating effect size (Cohen's d) of an intervention with scores obtained...

    Started by Ashok‎, 06-18-2013 10:34 PM
    effect size
    • Replies: 0
    • Views: 2,726
    06-18-2013, 10:34 PM Go to last post
  17. calculation of relative risk.

    ..........................Smokers...................Non- Smokers Iron Exopsure.......+..........-...................+..........- Lung...

    Started by Bahaa123‎, 05-19-2013 03:13 PM
    • Replies: 3
    • Views: 1,930
    06-18-2013, 09:31 AM Go to last post
  18. How to assess a new diagnostic test apart from ROC

    I have a diagnostic scoring system that uses 6 variables, each an ordinal or dichotomous value (some 0 to 1, others 0 to 4) (that when summed...

    Started by TS1‎, 06-14-2013 09:08 AM
    • Replies: 2
    • Views: 1,919
    06-14-2013, 12:14 PM Go to last post
  19. multicenter designs and power analysis

    Hello all, I am designing a study for examining the efficacy of a new treatment vs. a standard of care. For simplicity, let's say that my outcome...

    Started by NN_STAT‎, 06-04-2013 03:40 AM
    • Replies: 3
    • Views: 1,592
    06-13-2013, 07:53 PM Go to last post
  20. likelihood of false positive in Robust regression model. Gene expression results

    :shakehead Hi I'd like to calculate the probability of a gene A or genes A , B, C and D occuring due to chance alone in a genelist of concordant...

    Started by opsms‎, 06-13-2013 08:05 AM
    false discovery rate, gene expression, limma, microarray
    • Replies: 0
    • Views: 1,095
    06-13-2013, 08:05 AM Go to last post
  21. Can courtship behavior explain mating succes (Generalized Linear Model?)

    Hi. I'm trying to analyse some data about courtship behavior and mating succes in spiders. I have two groups of male spiders, well fed (NF) and...

    Started by Mann‎, 06-04-2013 12:33 PM
    • Replies: 2
    • Views: 1,239
    06-12-2013, 11:26 PM Go to last post
  22. SEM of 3 independent experiments

    Hi all... It's my first time to post in this forum. I would like to calculate the standard error of mean (SEM) of 3 independent experiments. ...

    Started by Matthewhk‎, 06-04-2013 08:57 AM
    • Replies: 1
    • Views: 2,748
    06-12-2013, 09:46 PM Go to last post
  23. Ecological changes in echinoderm populations: what statistical model is appropriate

    Hi Talk Stats and associated folks We are doing an ecological study on the effects of removal of an invasive seastar (Asterias amurensis) from...

    Started by Coastalresearch‎, 06-04-2013 09:26 PM
    • Replies: 7
    • Views: 2,595
    06-12-2013, 09:43 PM Go to last post
  24. How to build a regression model of survival data ?

    I would like to predict the response variable using different predictors. So far I have been working with multiple linear regression. However as my...

    Started by dada‎, 05-10-2013 06:11 AM
    censored
    • Replies: 1
    • Views: 1,889
    06-12-2013, 09:40 PM Go to last post
  25. What test to use?

    Hello everyone I need some help with a statistical analysis of two groups of time variables. So i have an unequal sample size with about 50...

    Started by felisleo‎, 06-06-2013 04:46 AM
    • Replies: 1
    • Views: 1,124
    06-12-2013, 09:13 PM Go to last post
  26. Wink Reducing likert-type scales from 10 point scale to lower order point scal

    Have made lots of movement in looking at this project... Overall Aim: To construct a clinical medical image scales (10 images in scale)...

    Started by Ailariz‎, 06-12-2013 06:53 PM
    decision trees, likert-type scale, multiple raters, neural networks
    • Replies: 0
    • Views: 2,138
    06-12-2013, 06:53 PM Go to last post
  27. association of binary data with multidimensional scaling?

    Hi everyone, I have 10 binary variables, each coding the presence or absence of an event for each of 2000 participants in the study. I would like...

    Started by mara79‎, 06-12-2013 03:07 AM
    • Replies: 3
    • Views: 3,579
    06-12-2013, 06:27 PM Go to last post
  28. Partial least squares regression with categorical variables?

    Hello, This is similar to a recent post about SNP data. I have genotype data based on SNPs (single nucleotide polymorphisms) for ~300 genetic...

    Started by RJoness‎, 05-16-2012 05:41 AM
    • Replies: 1
    • Views: 5,838
    06-12-2013, 02:13 PM Go to last post
  29. Appropriate tests for comparing 2 normally distributed datasets (ttest?)

    Hello, It's been a while since my A-level statistics course so I just want to make sure I'm doing the appropriate test for my data. I'm a PhD...

    Started by whathits‎, 06-12-2013 05:11 AM
    appropriate test, compare means, normal distribution, t-tests
    • Replies: 2
    • Views: 1,642
    06-12-2013, 08:23 AM Go to last post
  30. Percentages as a continuous variable

    Hello all I have a variable, on a continuous scale, it is some medical value before getting a treatment. After the treatment, this value is being...

    Started by NN_STAT‎, 06-11-2013 12:30 PM
    • Replies: 4
    • Views: 2,523
    06-12-2013, 01:55 AM Go to last post
  31. A better way to pick up on hidden variables

    Hi, I'm trying to determine cattle disease risk through various values, including weight, through a machine learning application. I have the usual...

    Started by shred14‎, 06-10-2013 01:05 AM
    • Replies: 1
    • Views: 1,484
    06-12-2013, 12:30 AM Go to last post
  32. topics for thesis in phd

    i am a phd student in biostatistics and i should choose a topic for my thesis but i am confused to choose a best topic. is any person to help me?

    Started by demyan‎, 06-07-2013 03:35 PM
    • Replies: 6
    • Views: 1,701
    06-09-2013, 12:36 PM Go to last post
  33. Survival Analysis (left censored data)

    Hello everybody, this is a question about survival analysis and although it is about a management science topic, I think the methodology fits in...

    Started by Cemon‎, 06-06-2013 04:52 AM
    • Replies: 0
    • Views: 1,844
    06-06-2013, 04:52 AM Go to last post
  34. Which analysis more suitable?

    Dear all, My data consists of 8000 rows and 14 columns, as follows: The rows correspond to quadruplicate measurements of 2000 variables and columns...

    Started by Paraskevi‎, 05-30-2013 08:05 AM
    anova, multiple comparisons, post hoc test
    • Replies: 1
    • Views: 1,508
    05-31-2013, 03:44 PM Go to last post
  35. Relative risk: lung cancer and smoking ! thanks in advance for your help

    .........................Smokers...................Non- Smokers Iron Exopsure.......+..........-...................+..........- Lung...

    Started by Bahaa123‎, 05-29-2013 01:37 PM
    • Replies: 3
    • Views: 3,845
    05-31-2013, 12:32 PM Go to last post
  36. Gehan-Breslow-Wilcoxon test or Cox regression

    Hello, I am looking at the relatively small dataset and comparing the survival of 2 groups of mice. The end survival is not very difference but it...

    Started by mousme‎, 05-28-2013 04:21 AM
    cox regression
    • Replies: 0
    • Views: 5,188
    05-28-2013, 04:21 AM Go to last post
  37. Distribution of a subset of the complete sample

    Dear all, My question can be easily misunderstood, so please allow me to briefly explain the experimental conditions. I have measured a...

    Started by ampws‎, 05-11-2013 04:54 AM
    data distribution, non-parametric test, parametric test, sample size
    • Replies: 4
    • Views: 2,426
    05-27-2013, 02:12 AM Go to last post
  38. Anova? Chi-square?

    Hi, I've been asked to analyze some data and I wanted to get a second opinion on the way I plan to. I have a sample of 8000 teachers. For each...

    Started by jamesmartinn‎, 05-10-2013 11:37 AM
    logit
    • Replies: 4
    • Views: 1,909
    05-26-2013, 05:55 AM Go to last post
  39. t-test or ANOVA in a validationstudy?

    Hello, i am doing reasearch for my bachelor thesis in physiotherapy and i need help with the statistics. my reasearch is about the validation of...

    Started by rolergirls‎, 05-24-2013 12:57 PM
    t-test, validationstudy
    • Replies: 4
    • Views: 1,529
    05-25-2013, 04:28 AM Go to last post
  40. Multivariate regression

    What is the most suitable way to assess the effect several independent ordinal variables have on a single nominal variable ? For example the...

    Started by KPW‎, 05-23-2013 08:11 AM
    regression, spss
    • Replies: 2
    • Views: 1,540
    05-23-2013, 09:45 AM Go to last post
  41. Colinearity, Logistic GEE

    Hi! I'm running a model and I think I've ran up against a colinearity issue. We have approximately 300,000 students in our dataset. For these...

    Started by jamesmartinn‎, 05-22-2013 04:48 PM
    • Replies: 1
    • Views: 2,358
    05-22-2013, 05:08 PM Go to last post
  42. Which stat? Difference of two means. T-test paired vs unpaired

    Hi guys. I'm trying to determine if the difference between two groups of data are statistically significant. Looking at mri, I am measure the...

    Started by detsb2011‎, 05-22-2013 09:22 AM
    • Replies: 2
    • Views: 3,206
    05-22-2013, 09:51 AM Go to last post
  43. Which stat test to use

    Hi all, I have a data set like this: Nematodes copepods Pylochaetes Controle1 1 ...

    Started by mr.twino‎, 05-15-2013 03:18 AM
    • Replies: 1
    • Views: 1,375
    05-17-2013, 05:55 AM Go to last post
  44. test to assess proportional difference over time between groups

    I am trying to determine the appropriate test to run for a community-based intervention. There are 2 groups (intervention and control) and 2 time...

    Started by ncresearch‎, 05-16-2013 05:02 PM
    • Replies: 1
    • Views: 1,887
    05-16-2013, 08:20 PM Go to last post
  45. Correct assessment of the sampling distribution of the mean for my experiment?

    Hi, all. I'm trying to properly analyze data from an experiment and could use some help bridging the mental gap between statistical theory (which I...

    Started by lnhstats‎, 05-14-2013 02:24 PM
    • Replies: 7
    • Views: 2,645
    05-15-2013, 06:21 PM Go to last post
  46. Enrichment analysis between two sets of proteins

    I'm trying to calculate a statistical measure describing the overlap of two sets of proteins. The issue is that the sets are from different organisms...

    Started by aarstar‎, 05-14-2013 11:32 PM
    • Replies: 5
    • Views: 2,312
    05-15-2013, 02:09 PM Go to last post
  47. Surgical Outcomes?

    Does anyone know a good SSPS tutorial for the project I'm doing? I want to do a retrospective study to see if Drug A reduced postoperative...

    Started by mdi455‎, 05-14-2013 05:56 PM
    spss tutorial
    • Replies: 2
    • Views: 1,106
    05-15-2013, 10:07 AM Go to last post
  48. How to estimate a population prevalence from several primary studies

    I have received point estimates from several studies for the prevalence of a rare disease, and I would like to estimate the over-all prevalence in...

    Started by AVoelp‎, 05-15-2013 02:30 AM
    confidence interval, prevalence
    • Replies: 0
    • Views: 1,189
    05-15-2013, 02:30 AM Go to last post
  49. Site, treatment,numbers before and after

    Hi I have data from an environmental experiment. We treated a section of river bed to remove an invasive species. I could do with some help...

    Started by rorys‎, 05-14-2013 09:46 AM
    before and after
    • Replies: 3
    • Views: 1,743
    05-14-2013, 11:57 AM Go to last post
  50. Using a repeated measures, two-way ANOVA.

    I want to compare the outcome of two different algorithms applied to one set of MRI images. Each MRI image will be manipulated twice. Once using the...

    Started by Araav‎, 05-12-2013 03:58 PM
    repeated measures, tukey, two-way anova
    • Replies: 0
    • Views: 1,974
    05-12-2013, 03:58 PM Go to last post
  51. Causal inference and survival analysis coursework

    Hey all, I'm an undergrad statistics student with an interest in causal inference topics such as propensity score analysis and instrument variable...

    Started by Birdnals‎, 05-04-2013 12:46 PM
    causal inference
    • Replies: 2
    • Views: 1,923
    05-09-2013, 04:05 PM Go to last post
  52. Correlation analysis

    Hi, First I have to apologise for the probably stupid question, but my statistic knowledge is pretty much 0 and after searching for an answer for...

    Started by Jeannine‎, 05-06-2013 07:32 PM
    cluster analysis
    • Replies: 2
    • Views: 1,850
    05-09-2013, 03:05 PM Go to last post
  53. Smile Correlation between lines:Odd man out

    Dear Friends, I am analyzing the presence of cis element in 1K upstream of some up regulated genes. I have got the number of elements in the...

    Started by Vinay‎, 05-08-2013 04:52 AM
    • Replies: 1
    • Views: 1,313
    05-08-2013, 09:28 PM Go to last post
  54. Survival analysis: how do i include a random effect and interval censoring?

    Hi, I'm trying to use some form of survival analysis (e.g. accelerated failure time or proportional hazards) to study seed germination time. My...

    Started by Tarek‎, 05-08-2013 01:43 PM
    frailty, grouped-time, interval censoring, proportional hazard, sas, survival analysis
    • Replies: 0
    • Views: 1,222
    05-08-2013, 01:43 PM Go to last post
  55. Graphs, Funnel Plots, suggestions?

    Hi! I'm trying to display some data, let me describe it to you. I have a group of about 5000 teachers. For each teacher, I have the rate of...

    Started by jamesmartinn‎, 05-07-2013 11:12 AM
    funnel plot
    • Replies: 4
    • Views: 1,975
    05-07-2013, 12:54 PM Go to last post
  56. Incidence & competing risks

    Hello, I'm a bit puzzled about competing risks. I've used competing risks methods (gray's test and fine and gray regression) a while ago, but...

    Started by anker‎, 05-06-2013 05:41 AM
    • Replies: 0
    • Views: 2,188
    05-06-2013, 05:41 AM Go to last post
  57. how to test 2x2 table with an one empty cell in admission patients?

    I am a clinician working for a community based hospital. A few days ago, my fellow doctor asked me if I could give some advice for her data. ...

    Started by navyblue00‎, 05-02-2013 08:20 PM
    fisher's exact test
    • Replies: 1
    • Views: 4,033
    05-05-2013, 06:55 AM Go to last post
  58. How to normalize LC-MS data with minimum bias (proteomics)

    Hello all, I'm working with quantification of some modified peptides enriched from serum of sick and healthy people. In the crude data (integrated...

    Started by hkontro‎, 04-24-2013 12:40 PM
    normalization, proteomics, quantification
    • Replies: 8
    • Views: 7,839
    05-03-2013, 04:32 AM Go to last post
  59. Mean Residual Life

    Hi, I've been tasked with solving the mean residual life given the density function f(x) and the survival function S(x) I think mean residual...

    Started by chinarider25‎, 05-01-2013 02:00 PM
    mean residual life, mrl, stat, survival
    • Replies: 0
    • Views: 1,635
    05-01-2013, 02:00 PM Go to last post
  60. Survey

    I'm a Biostatistician working for a researcher who wants to find out if length of training would affect peoples opinion in choosing a certain medical...

    Started by ccasboy30‎, 05-01-2013 11:38 AM
    • Replies: 2
    • Views: 1,740
    05-01-2013, 12:38 PM Go to last post

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