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Forum: Biostatistics

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

  1. Best Statistical test for data

    Hi All, Just wondering if someone could help with an issue with my data. I am wanting to analyse the relationship between continuous variable...

    Started by HRS‎, 05-25-2016 03:48 AM
    • Replies: 3
    • Views: 144
    Yesterday, 06:49 AM Go to last post
  2. ANCOVA assmptions not met.

    Hi, What is the non parametric alternative for parametric ANCOVA if we find that some ANCOVA assumptions are not met? How it can be done in SAS?

    Started by shruti verma‎, 05-25-2016 03:46 AM
    analysis, analysis of covariance, ancova, assumptions
    • Replies: 1
    • Views: 70
    05-25-2016, 04:03 AM Go to last post
  3. Score methods

    Hello everyone, I would like your opinion. my data is score (before and after therapy) on radiographs made with x-ray instrument and score based on...

    Started by andrew_fg‎, 05-23-2016 01:47 PM
    • Replies: 2
    • Views: 124
    05-24-2016, 01:55 PM Go to last post
  4. Please help me selecting a test for my study

    Hi, I was wondering if you guys can provide some ideas on best test for my samples size, since I am not very stat savvy. My project consist of...

    Started by kite6k‎, 05-18-2016 12:07 PM
    • Replies: 4
    • Views: 171
    05-24-2016, 09:03 AM Go to last post
  5. Frequency analysis

    Hello. I have a problem with my analysis. I got 2 groups which take drug (Group 1 (50 people) takes real medicine and Group 2 (40 people) takes...

    Started by Makina‎, 05-20-2016 04:50 AM
    • Replies: 7
    • Views: 229
    05-23-2016, 08:12 AM Go to last post
  6. Paired or Unpaired T-test?

    If I have traps set to capture a certain animal at night vs. during the day, would I use a paired or unpaired T-test? I'd be comparing the mean...

    Started by OMai‎, 05-22-2016 10:59 AM
    paired, t-test, unpaired
    • Replies: 1
    • Views: 100
    05-22-2016, 12:47 PM Go to last post
  7. 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...

    Started by bluina‎, 05-11-2016 03:38 AM
    biostatistics, multivariate analysis, non parametric
    • Replies: 4
    • Views: 231
    05-20-2016, 04:07 AM Go to last post
  8. Which statistical test shoud I use?

    I have concentrations of one metal in two organs of a snail – kidney and foot (n=10). What statistical test should I use to check if the difference...

    Started by Miii‎, 05-19-2016 06:36 AM
    • Replies: 7
    • Views: 173
    05-19-2016, 02:27 PM Go to last post
  9. LD50 and ED50 calculation with Probit and other methods

    hello All i'm not have good experiences in bio-statistic and want to know how can i calculate LD50 for Bacteria and ED50 for Bacterial Vaccine...

    Started by mazan2010‎, 05-18-2016 01:19 PM
    • Replies: 0
    • Views: 89
    05-18-2016, 01:19 PM Go to last post
  10. 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...

    Started by GN1‎, 05-17-2016 01:43 AM
    biostatistics, research article
    • Replies: 1
    • Views: 141
    05-18-2016, 08:26 AM Go to last post
  11. Metal accumulation dependence on weight and pollution

    I'm working on metal accumulation in two landsnail species and it includes their kidneys and feet. I have concentrations of 7 metals in these organs...

    Started by Miii‎, 05-18-2016 04:42 AM
    • Replies: 1
    • Views: 156
    05-18-2016, 07:26 AM Go to last post
  12. I do not know how to calculate my sample size…

    Hello, can someone help me calculate my sample size and showing me the steps of how it should be done? I am going to do a study to see a...

    Started by Maria voltaren‎, 05-16-2016 04:37 AM
    sample size calculation
    • Replies: 0
    • Views: 103
    05-16-2016, 04:37 AM Go to last post
  13. Query about RRs and confounders

    Hi I am doing my head in over something very simple. Its more theoretical and I'm trying to work out a method. I am hoping someone can clarify...

    Started by statsanon‎, 05-15-2016 07:02 PM
    • Replies: 0
    • Views: 92
    05-15-2016, 07:02 PM Go to last post
  14. Question Safety or efficacy outcome?

    Dear friends, I got confused regarding outcome study I had to review. The primary outcome is: Time to the first occurrence of any of the...

    Started by wellfor‎, 05-14-2016 12:47 PM
    efficacy, outcome, safety
    • Replies: 0
    • Views: 89
    05-14-2016, 12:47 PM Go to last post
  15. Statistical test for proportions (values' range: 0-1)

    I am trying to compare mass spec data from 3 different conditions. For each protein I detected in my samples I have 3 values/condition (from 3...

    Started by jalbertortega‎, 05-13-2016 12:54 PM
    • Replies: 1
    • Views: 139
    05-14-2016, 09:10 AM Go to last post
  16. chi-square test

    Hi, can somone help me with doing a Chi-square test or Yates corrected chi-square test of the data file attached. I dont get it, or is the test...

    Started by Anne3‎, 05-12-2016 07:33 AM
    • Replies: 0
    • Views: 130
    05-12-2016, 07:33 AM Go to last post
  17. Problems in Cox proportional hazards model, Survival analysis.

    Hello everyone, I got trouble with some problems as following Suppose a Cox proportional hazards model was fit with 2 covariates, smoking status...

    Started by Leon Yo‎, 04-24-2016 12:39 PM
    • Replies: 1
    • Views: 183
    05-11-2016, 12:33 AM Go to last post
  18. Repeated measures with one between subject and two within subject factors

    I have measured plasma cortisol levels in blood samples collected at an interval of 1 hour over a period of 24 hours in 10 male and female animals...

    Started by Bharath‎, 05-02-2016 06:05 PM
    • Replies: 2
    • Views: 263
    05-08-2016, 08:27 PM Go to last post
  19. Bootstrap strange estimate

    Hello everyone, I'm a statistical novice, I would like your help. I'm analyzing non-normally distributed variables. To develop the confidence...

    Started by andrew_fg‎, 05-06-2016 12:52 PM
    • Replies: 5
    • Views: 246
    05-06-2016, 06:40 PM Go to last post
  20. Best way to calculate power, precision & sample size using complex pilot data set?

    I have a large and complex pilot data set of electromyographic (EMG) data collected from human subjects performing several different exercises. A...

    Started by statsSeeker‎, 04-29-2016 01:47 PM
    power, precision, sample size calculation, sample size determination
    • Replies: 2
    • Views: 236
    05-05-2016, 01:16 PM Go to last post
  21. should I include a table with non significant results of Z proportion tests

    I am writing a manuscript and have a table with ONLY non significant Z proportion test results. I am wondering whether to omit this table although it...

    Started by Moranke‎, 05-02-2016 03:34 AM
    • Replies: 1
    • Views: 144
    05-05-2016, 07:26 AM Go to last post
  22. Diagnostic accuracy of two methods tested on longitudinal data/repeated measurements

    To compare two imaging rating methods in detecting growth (ordinal variable + , = , - ) we compared serial MRI's with both methods. We have for...

    Started by SophieBel‎, 02-09-2016 12:24 PM
    • Replies: 2
    • Views: 410
    04-26-2016, 06:06 PM Go to last post
  23. URGENT: What are the statistical limits and biases in this scientific article?

    I need to deliver this exercise in the next 10 hours. QUESTION: What are the statistical limits and biases in this scientific article, which...

    Started by pericles‎, 04-26-2016 01:21 PM
    articles, bias, inference, limits, publication
    • Replies: 0
    • Views: 147
    04-26-2016, 01:21 PM Go to last post
  24. Estimating discordant pairs for McNemar's test sample size

    Dear Friends, This is my first time posting ;) I want to use McNemar's test to determine if diagnostic test A or B has better sensitivity and...

    Started by Aquaman29‎, 04-24-2016 05:57 PM
    • Replies: 0
    • Views: 178
    04-24-2016, 05:57 PM Go to last post
  25. ANOVA RCB design; multiple items in groups

    Good day! I have a study that seems to fit the criteria for an ANOVA using a randomized complete block design. The research is on the effect of...

    Started by Johann Kotze‎, 04-24-2016 06:50 AM
    anova, rcb
    • Replies: 0
    • Views: 114
    04-24-2016, 06:50 AM Go to last post
  26. Systematic component variation

    The appendix of the paper of contains a derivation of the systematic component variation SCV. I understand the derivation with exception of the...

    Started by giordano‎, 04-15-2016 02:31 AM
    estimation, variance, variance components
    • Replies: 0
    • Views: 333
    04-15-2016, 02:31 AM Go to last post
  27. Exclamation Inoculated chickens-bacterial load. Non Linear Mixed Model with repeated measures?

    :wave: Help! I have some data I am trying to analyze but was hoping to get some stats help with it. I'm not sure what the best way to analyze it is....

    Started by vet_11‎, 04-13-2016 03:45 AM
    bacterial load; k-wallis, mixed effects model
    • Replies: 0
    • Views: 212
    04-13-2016, 03:45 AM Go to last post
  28. Help with SAS, MANOVA, and Habitat Selection

    Hello everyone, I guess my long story short is does anyone have any experience using SAS to run a MANOVA to determine habitat selection. I have...

    Started by Esoxdiver‎, 04-08-2016 07:19 PM
    • Replies: 0
    • Views: 292
    04-08-2016, 07:19 PM Go to last post
  29. Prognostic study in Imminent Bain Death (IBD)

    Dear all, I am new in this forum. I have an ongoing research and I am dealing with the statistic. In our study we are trying to compare 2...

    Started by pivadoc‎, 04-06-2016 02:56 PM
    • Replies: 0
    • Views: 258
    04-06-2016, 02:56 PM Go to last post
  30. Question regarding p-value interpretation in Group Sequential Designs

    Hello everyone. I have a general question that I would appreciate any input on: Suppose we design a typical group sequential design and to stop...

    Started by trekvana‎, 03-29-2016 03:36 PM
    • Replies: 0
    • Views: 350
    03-29-2016, 03:36 PM Go to last post
  31. Paired analysis of Proportions with Gold Standard Retest

    Greetings :) I'm working on developing a diagnostic test. I have a small clinical dataset that was evaluated with the diagnostic test and a...

    Started by Midgardian‎, 03-29-2016 12:58 PM
    • Replies: 0
    • Views: 173
    03-29-2016, 12:58 PM Go to last post
  32. Sample size calculation in a 3 group parallel clinical trial

    Hello everyone. I'm having trouble with biostatistics in general but particularly with finding out how to calculate what sample size i need in...

    Started by TNK78‎, 03-27-2016 02:58 PM
    • Replies: 8
    • Views: 573
    03-28-2016, 03:21 PM Go to last post
  33. Comparing groups - which test should I use - one-way or two-way ANOVA

    Here is the experiment sum-up: we transplanted limb from one rat to another (n=5 per group), the goal was to find out which treatment was the best in...

    Started by Nataliya‎, 03-28-2016 12:39 PM
    • Replies: 0
    • Views: 155
    03-28-2016, 12:39 PM Go to last post
  34. Predictive value of X for a change in Y?

    Hi everyone, R question: 10 participants underwent a weight loss programme, like so: ...

    Started by RodeLoper‎, 03-24-2016 01:39 PM
    intercept, random effects model, slope
    • Replies: 1
    • Views: 278
    03-25-2016, 02:47 AM Go to last post
  35. Statistical test of difference among values from multiple timepoints

    Hello, I have a question on selecting a statistical test. I am trying to assess changing abundance of microbes in oral cavity along time. My...

    Started by 3toedsloth‎, 03-23-2016 05:25 PM
    • Replies: 0
    • Views: 210
    03-23-2016, 05:25 PM Go to last post
  36. Comparing new and old medical equipment

    ***I'm not sure why this posted twice (and I don't know how to delete this one), but please see the other post with the image attached. Thank...

    Started by DataMom‎, 03-20-2016 05:41 AM
    • Replies: 3
    • Views: 385
    03-20-2016, 11:56 AM Go to last post
  37. Survey regression modeling rates

    I have a nationally representative data set of ~30,000 emergency department visits in a year; using the provided weights, these represent ~200...

    Started by subharimc‎, 03-18-2016 11:39 AM
    • Replies: 0
    • Views: 226
    03-18-2016, 11:39 AM Go to last post
  38. Research methodology question

    We are implementing a new community healthcare program at work in order to reduce hospital attendances and admissions. The program began in June...

    Started by scotchpie‎, 03-17-2016 09:56 AM
    • Replies: 2
    • Views: 255
    03-17-2016, 11:30 AM Go to last post
  39. Power analysis and Kaplan meier

    Hello! I need your help to compute a power analysis for survival analysis (Kaplan meier) without historical data. In my lab we are preparing a...

    Started by Fischer‎, 03-17-2016 09:00 AM
    • Replies: 0
    • Views: 175
    03-17-2016, 09:00 AM Go to last post
  40. best modeling approach?

    I have a data set with about 5000 pts and trying to create a risk prediction model to predict binary outcome that does not have competing risks...

    Started by viostorm‎, 03-15-2016 05:31 PM
    • Replies: 5
    • Views: 482
    03-16-2016, 07:53 PM Go to last post
  41. Is my study a case control or a cohort study?

    Hi everyone. I'm a student with very little experience or background in biostatistics. My mind is in a bit of a bind and I can't seem to be able to...

    Started by sadrith‎, 03-16-2016 01:01 PM
    • Replies: 1
    • Views: 217
    03-16-2016, 02:22 PM Go to last post
  42. Repeated measure ANOVA

    Hello guys, Haven’t done stats for 15 years, and been struggling for weeks now on an ANOVA, lost in a rural area in Haiti with limited access to...

    Started by Libellule‎, 03-15-2016 04:46 PM
    • Replies: 2
    • Views: 202
    03-16-2016, 09:09 AM Go to last post
  43. Computing effect size with adverse event counts?

    Hello! I'm working on a meta-analysis, and I have a special problem regarding effect size. Can anyone lend me some insight? I have a treatment...

    Started by wag‎, 03-14-2016 02:26 PM
    • Replies: 0
    • Views: 211
    03-14-2016, 02:26 PM Go to last post
  44. estimate 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...

    Started by andrew_fg‎, 03-12-2016 04:42 AM
    biostats, estimate
    • Replies: 1
    • Views: 264
    03-12-2016, 06:00 AM Go to last post
  45. Wink Justification for t-tests instead of 2-way ANOVA (no interaction)

    HI there, I need help with justification for why I should use a t-test instead of a two-way ANOVA. My two-way ANOVA gave me a main effect of Diet...

    Started by dulcedumbre‎, 03-11-2016 10:05 AM
    justification, no interaction, t-test, two-way anova
    • Replies: 3
    • Views: 259
    03-11-2016, 12:43 PM Go to last post
  46. An associate for publishing studies?

    Hello friends. I am a Ph.D. student in medicine. Untill now I have published four scientific papers (two of them, meta-analyses). I have also...

    Started by bioresearcher‎, 03-11-2016 09:07 AM
    • Replies: 0
    • Views: 148
    03-11-2016, 09:07 AM Go to last post
  47. sample size calculations

    So, i'm in the process of setting up a trial comparing two different methods of observation and I need to calculate the sample size. I plan on...

    Started by sigge weisdorf‎, 03-11-2016 07:48 AM
    • Replies: 0
    • Views: 124
    03-11-2016, 07:48 AM Go to last post
  48. Correcting for a confounding factor in a retrospective laser eye surgery study

    Hello, I would really appreciate some help on study design. I will present my ideas and if the forum could critique/advise I would be very...

    Started by eyedocdan‎, 03-04-2016 01:37 PM
    • Replies: 5
    • Views: 626
    03-06-2016, 09:49 PM Go to last post
  49. statistical test for a cancer vs normal comparison from the same patient

    Hello, I have a question concerning which statistical test is best for analyzing my data. I measured the activity of an enzyme in primary cells...

    Started by vanida‎, 02-27-2016 04:33 PM
    • Replies: 2
    • Views: 459
    03-05-2016, 04:33 PM Go to last post
  50. Interpreting Kruskal-Wallis test

    My question arises from a paper I read. Two groups are compared using the non-parametric Kruskal-Wallis test. Neither group has data that is normally...

    Started by JRA‎, 03-01-2016 01:16 PM
    • Replies: 7
    • Views: 471
    03-04-2016, 01:47 AM Go to last post
  51. Small sample: Descriptive or analytical? Adjust or not?

    Hi, I need help with choosing which tests to use, as well as the goal of the testing. I am sure some of my questions are answered already on this...

    Started by teapot‎, 03-01-2016 11:11 PM
    • Replies: 1
    • Views: 289
    03-02-2016, 05:41 AM Go to last post
  52. Question regarding sample in EBP project

    Hi, I was hoping someone could provide me with some insight for an evidence based practice project I am working on. I'm currently appraising...

    Started by abreckenridge‎, 03-01-2016 12:46 PM
    • Replies: 1
    • Views: 180
    03-01-2016, 01:12 PM Go to last post
  53. please help me justify sample size for a pilot clinical trial

    I'm a bit desperate for statistical help so trying out all avenues. Any guidance appreciated! I need to justify a sample size of 30 or 32 (15 or...

    Started by trancine‎, 03-01-2016 07:43 AM
    clinical trial, confidence intervals, effect size, power analysis, sample size
    • Replies: 2
    • Views: 248
    03-01-2016, 10:39 AM Go to last post
  54. By wastewater treatment microbial technology

    :làn sóng: Wastewater from residential areas, urban collection tank was brought before collection tank sewage systems of automatic duplex to separate...

    Started by moitruongtnt‎, 02-27-2016 10:58 AM
    wastewater treatment
    • Replies: 0
    • Views: 188
    02-27-2016, 10:58 AM Go to last post
  55. Adjusting for clustered observations

    Hello, I have collected mortality data and several covariates (data on treatment and vital parameters) from patients in two different hospitals....

    Started by Patrick‎, 02-22-2016 02:52 AM
    fixed effect, gee, logistic regression, random effect
    • Replies: 5
    • Views: 378
    02-25-2016, 11:17 AM Go to last post
  56. Smile Selecting an appropriate spatial scale in landscape ecology!?

    Hello, I am currently studying the effect of organic farming on honeybee colonies. I have calculated the percentage of organic land in several...

    Started by master student‎, 02-25-2016 08:27 AM
    data mining, landscape ecology, spatial scale
    • Replies: 0
    • Views: 180
    02-25-2016, 08:27 AM Go to last post
  57. Am I introducing a selection bias in my prognostic biomarker study ?

    Hi all, I'd be glad to get the advice from someone who's better than me at biostatistics, especially regarding selection biases in survival...

    Started by Debby 02‎, 02-23-2016 04:14 PM
    • Replies: 5
    • Views: 336
    02-24-2016, 08:12 AM Go to last post
  58. Cox regression with 6 variables in 30-something patients sample, is it legitimate?

    Hi, I'm doing some research and I have a sample of 33 patients. I'm testing an association of one new parameter (let's call it X) on survival and...

    Started by Markica85‎, 02-21-2016 05:25 PM
    • Replies: 0
    • Views: 234
    02-21-2016, 05:25 PM Go to last post
  59. Kruskal-Wallis and post-hoc tests

    Hi, Can I do post-hoc tests, such as Scheffé's test, while I'm performing a Kruskal-Wallis test? Thanks.

    Started by Biologist‎, 02-19-2016 03:20 PM
    • Replies: 2
    • Views: 319
    02-21-2016, 06:33 AM Go to last post
  60. How meaningful is to pool data from different surveys on the same target population?

    HI everybody, this is a very theoretical question for me but I would like to find an answer as I might want to use this in the (near) future. In...

    Started by Ralph84‎, 02-15-2016 12:50 PM
    pooled estimates, pooling data, survey weights
    • Replies: 3
    • Views: 368
    02-16-2016, 04:06 AM Go to last post

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