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Forum: Biostatistics

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

  1. Normal Approximation, Fisher's Exact Test, Relative Risk or Odds Ratio?

    A clinical trial is being planned, in which the primary outcome is binary (success/failure). There are two treatment groups (treatment/control). The...

    Started by WeeG‎, 06-17-2017 01:06 PM
    • Replies: 6
    • Views: 288
    06-18-2017, 11:57 AM Go to last post
  2. sample size calculation for chi square test with more than 2 groups

    Greetings everybody I'm running a sample size estimation for a study that will use chi square test of association for the qualitative comparison of...

    Started by Bassam‎, 06-07-2017 06:23 PM
    • Replies: 4
    • Views: 415
    06-08-2017, 10:58 AM Go to last post
  3. Poisson Standard Deviation

    Hi! Just a sanity check as I have to do a few computations for a report manually. Our indicator is defined in the following way: #...

    Started by jamesmartinn‎, 06-05-2017 10:03 AM
    • Replies: 5
    • Views: 352
    06-05-2017, 02:45 PM Go to last post
  4. test for cumulative analysis of outcomes over time in meta-analysis

    A systematic review and meta-analysis I am reading references having tested for chronological cumulative analysis for the effects of the outcomes...

    Started by Roundtoit‎, 06-02-2017 05:41 PM
    • Replies: 3
    • Views: 273
    06-04-2017, 03:02 PM Go to last post
  5. Simple question re retrospective study types

    Hi, Please could someone confirm that I'm using the correct terminology to describe two studies listed below. I think that they are both...

    Started by ConnemaraPony‎, 05-30-2017 01:31 PM
    • Replies: 2
    • Views: 336
    05-30-2017, 03:48 PM Go to last post
  6. Non Inferiority with a Historical Control

    Is it possible or valid to do a Non-Inferioirty Test againts a historical control. I should point out for the historical control all I have is a...

    Started by polc1410‎, 05-30-2017 04:09 AM
    • Replies: 1
    • Views: 197
    05-30-2017, 08:46 AM Go to last post
  7. Should I perform a PCA on my datas?

    Hi, I'm new to the statistic world. I have doubts about pca. I am performing the statistics of my study and I have a lot of data. I wonder if I can...

    Started by Clarissa‎, 05-26-2017 08:36 AM
    • Replies: 0
    • Views: 268
    05-26-2017, 08:36 AM Go to last post
  8. covariate for only clinical group

    HI I have tried to find an answer on the web but was not able, and will appreciate your help! I have a question regarding the use of a covariate in...

    Started by newbeeme‎, 05-21-2017 01:48 AM
    • Replies: 3
    • Views: 445
    05-22-2017, 09:28 AM Go to last post
  9. Absolute values or Log-transformed data

    I want to perform a non parametric test (mann-whitney) for my experiments that is briefly quantification of viral load (Real Time Polymerase chain...

    Started by julian_DE‎, 05-15-2017 01:06 AM
    • Replies: 3
    • Views: 447
    05-15-2017, 08:55 PM Go to last post
  10. Smile Mixed Model Analysis SPSS

    Hello All, I have a data set which I am trying to find out what is the best way to go about analyzing. I have been asking around and was advised...

    Started by quix09‎, 05-15-2017 08:24 AM
    • Replies: 0
    • Views: 247
    05-15-2017, 08:24 AM Go to last post
  11. Is Cochran's Q the right test for repeated measures with binary outcomes?

    Hi, I am trying to analyze a data set. The question we are looking at is whether the rate of a successful outcome and the risk of a...

    Started by Jennifer Kosty‎, 05-12-2017 12:15 PM
    • Replies: 0
    • Views: 250
    05-12-2017, 12:15 PM Go to last post
  12. Different proportions in different conditions?

    Hi, I am struggling with the proper way to analyze my data. I did some research in and out of this forum but could not find the answer to my...

    Started by Fanny-‎, 04-11-2017 08:06 AM
    • Replies: 3
    • Views: 737
    05-07-2017, 03:06 AM Go to last post
  13. GLM with non-linear predictor

    Hi, I am analyzing a dataset looking at procedural skill development. The data itself is binomial, whether or not a procedure was successful. When...

    Started by amw2320‎, 05-06-2017 11:02 PM
    • Replies: 0
    • Views: 304
    05-06-2017, 11:02 PM Go to last post
  14. Contingency tables with proportions only

    Hi, I have a 3x2 contingency table, which contains the observed and expected allele frequencies from a hypothetical population and I'd like to test...

    Started by Acather96‎, 05-04-2017 02:23 PM
    • Replies: 8
    • Views: 477
    05-04-2017, 05:59 PM Go to last post
  15. Post Chi-square goodness of fit test

    Hi all, I'm currently conducting research at a radiology department. The setup of our research is that we let 2 radiologists indicate their...

    Started by MaxTalksStats‎, 05-01-2017 03:29 AM
    • Replies: 1
    • Views: 432
    05-01-2017, 04:23 AM Go to last post
  16. Association/ correlation binary and continuous data non-normal distribution

    Hi, I want to perform an association analysis between a binary (dichotomous?) variable and continuous variable. The binary variable is whether...

    Started by Hannah212‎, 04-27-2017 03:37 AM
    binary, continuous, correlation analysis, point-biserial
    • Replies: 5
    • Views: 460
    04-27-2017, 02:59 PM Go to last post
  17. Wink Antibiogram

    greetings :yup: im doing a documentary review of the Clinical Profile and Antibiogram Pattern of Patients With Diabetic Foot Ulcers. Problem is, I...

    Started by otepmeimban‎, 04-27-2017 12:44 PM
    • Replies: 1
    • Views: 280
    04-27-2017, 01:02 PM Go to last post
  18. what statistical test to choose

    Hi all, I am working on a similar kind of project as this https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4313376/ For table 2, what are the...

    Started by bburugap‎, 04-24-2017 02:15 PM
    • Replies: 0
    • Views: 380
    04-24-2017, 02:15 PM Go to last post
  19. Can i use one sample t-test?

    Hi all Currently im doing a research to see how effective my results as compared to the mean value and standard deviation of previous study. ...

    Started by hnw‎, 04-20-2017 04:41 AM
    one sample t test
    • Replies: 2
    • Views: 498
    04-20-2017, 08:16 AM Go to last post
  20. Question 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...

    Started by romes‎, 03-25-2017 10:23 AM
    biostatistics, reference interval
    • Replies: 1
    • Views: 618
    04-16-2017, 08:32 AM Go to last post
  21. 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...

    Started by robertp‎, 04-15-2017 11:04 AM
    biostatistics, data analysis, nmri, normalization, proteomics
    • Replies: 0
    • Views: 266
    04-15-2017, 11:04 AM Go to last post
  22. Bias Question

    My statistics teacher and I are at a disagreement with an answer to one of his questions and I was wondering if you all could help me out. The...

    Started by jimsam321‎, 04-12-2017 04:55 PM
    • Replies: 14
    • Views: 579
    04-13-2017, 09:29 AM Go to last post
  23. Question Comparing groups - Should I do hypotesis testing on raw counts or percentage values?

    Hi, first post here, and I really hope you can help me with this. I'm measuring the number of cells labelled with two markers (let's call them A...

    Started by sgomes‎, 04-10-2017 10:37 AM
    • Replies: 3
    • Views: 443
    04-10-2017, 04:57 PM Go to last post
  24. Chi Square test (not significant when comparing across 4 groups but changes with 2)

    Hi all, I was conducting a chi-square + fisher test and ran across a problem: I am using a chi square to test whether or not there is an...

    Started by Nives_ES‎, 04-07-2017 11:45 AM
    • Replies: 2
    • Views: 489
    04-07-2017, 02:08 PM Go to last post
  25. Statistical help (not independent samples)

    Hello all, I need some help in understanding what statistical test to use when I have 3 groups and the groups are not independent of each other...

    Started by bburugap‎, 04-01-2017 02:40 PM
    • Replies: 2
    • Views: 537
    04-05-2017, 04:04 PM Go to last post
  26. How to do age standardization for morbidity study (2 populations)

    Good day all, I have a question in regards to age standardization. My study is on morbidity(disease) and I have 2 populations. The populations are...

    Started by happiness17‎, 04-04-2017 04:47 AM
    • Replies: 0
    • Views: 362
    04-04-2017, 04:47 AM Go to last post
  27. Unhappy Which test for equivalency?

    I have two machines A & B. 5 patients. I calculate the elasticity of their skin with the two different machines. This gives me two numbers per...

    Started by yolo123‎, 04-01-2017 07:00 PM
    • Replies: 6
    • Views: 614
    04-02-2017, 04:15 PM Go to last post
  28. PCA questions?

    Hi there, I am a bit new to statistics and have a few questions. I am currently doing my dissertation on the consistent and variable...

    Started by Callum94‎, 03-29-2017 12:59 PM
    • Replies: 3
    • Views: 720
    03-29-2017, 06:36 PM Go to last post
  29. Predicting outcome with multiple groups

    Hi everyone, I'm currently working with 3 different groups (3 disease populations) and I would like to predict which of the three groups they fall...

    Started by Eric2014‎, 03-28-2017 12:14 PM
    groups, logistic, prediction, regression
    • Replies: 4
    • Views: 542
    03-28-2017, 03:45 PM Go to last post
  30. Finding data given sample mean and variance

    Hello, I have a problem, I am given the sample size, mean, variance, and I know it is normally distributed. The question states that 160...

    Started by dorothy8‎, 03-26-2017 06:56 PM
    • Replies: 2
    • Views: 465
    03-27-2017, 09:56 PM Go to last post
  31. am i overadjusting?

    might sound silly but for my research topic I am looking into insulin resistance (IR) and dietary factors. We are measuring IR by the use of...

    Started by jkerr1‎, 03-27-2017 04:56 AM
    • Replies: 1
    • Views: 442
    03-27-2017, 10:23 AM Go to last post
  32. Confidence interval question

    Fr a sample of 100 hypertensive patients, we find that a 95% confidence interval of systolic BP to be . What statement is FALSE? A- if a drug is...

    Started by dorothy8‎, 03-26-2017 05:53 PM
    • Replies: 1
    • Views: 404
    03-27-2017, 02:20 AM Go to last post
  33. Pre and post comparison for nonparametric unpaired sample

    Hi. I am not sure how to compare the results from the following study. Number of wrong orders out of total orders placed every day for 60 days as...

    Started by anupamsule‎, 03-22-2017 09:01 PM
    • Replies: 2
    • Views: 710
    03-24-2017, 07:04 AM Go to last post
  34. Dealing with Log(0)

    Dear all, Iíve been stuck for quite some time with a problem that relates to use of log-scale with values that equal zero. My data comes from an...

    Started by ritmaniac‎, 03-21-2017 07:21 AM
    anova, linear regression, logarithmic
    • Replies: 2
    • Views: 655
    03-21-2017, 04:22 PM Go to last post
  35. Sample size calculation for 1:2 matched case-control study

    Hi, I have a matched case-control study with 12 cases and two controls for each case. Evaluating our findings, I want to calculate what our sample...

    Started by teapot‎, 03-08-2017 02:22 PM
    • Replies: 7
    • Views: 1,193
    03-17-2017, 08:59 AM Go to last post
  36. stratified log-rank test and proportional hazards

    Does stratified log-rank test overcome problem of violation of proportional hazards? I encountered a randomized controlled study of a new drug...

    Started by Markica85‎, 03-16-2017 04:53 AM
    • Replies: 0
    • Views: 574
    03-16-2017, 04:53 AM Go to last post
  37. Regarding Maximum Percent different

    Dear all, Could you please explain what maximum percent different for continues vital DiaBP data. How to calculate this? Could you any one...

    Started by Statvijay‎, 03-14-2017 07:08 AM
    • Replies: 0
    • Views: 491
    03-14-2017, 07:08 AM Go to last post
  38. Survival Analysis - Time to utilization of medical services

    Hi all, I work in the medical field and Iím looking into using survival analysis calculate time to utilization of medical services, that is, once...

    Started by avbraga‎, 03-10-2017 04:35 PM
    • Replies: 6
    • Views: 751
    03-13-2017, 06:07 PM Go to last post
  39. vision in eyes at different times

    Hi everyone, New to the forum and am seeking a bit of guidance as to how to compare vision (visual acuity) between eyes. So I am trying to...

    Started by jksgoh‎, 03-11-2017 02:44 AM
    • Replies: 1
    • Views: 560
    03-13-2017, 02:42 PM Go to last post
  40. Which statistical tests are appropriate: Group means before and after treatment

    I am trying to find out what statistical tests to run on a set of aggregate data (no individual data) on 3 different groups, variables are summarized...

    Started by PamelaF‎, 03-07-2017 04:17 AM
    • Replies: 1
    • Views: 832
    03-09-2017, 04:31 PM Go to last post
  41. Adjustment for correlated data in meta-anlaysis

    Hi, I'm completing a systematic review and performing meta-anlaysis forest plots. The research question related to the finding of risk factors for...

    Started by Ainslie‎, 03-08-2017 12:47 AM
    adjustment, correlated data, meta-analysis
    • Replies: 2
    • Views: 783
    03-08-2017, 11:07 AM Go to last post
  42. standard deviation greater than variance, is this ok?

    I am putting together some audit results and it was suggested I present them as mean +/- SD. However there is a significant variance in the results....

    Started by Roundtoit‎, 03-07-2017 05:44 PM
    • Replies: 7
    • Views: 1,213
    03-08-2017, 04:23 AM Go to last post
  43. Comparing diagnostic tests - graphically demonstration

    Hi, This is very basic but really struggling to find the correct terminology to find out what I want to do. I have collected data on two methods...

    Started by k093‎, 03-07-2017 07:17 PM
    • Replies: 0
    • Views: 537
    03-07-2017, 07:17 PM Go to last post
  44. 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...

    Started by Roundtoit‎, 03-05-2017 03:10 PM
    biostatistics, cohort study, risk difference
    • Replies: 1
    • Views: 905
    03-05-2017, 04:02 PM Go to last post
  45. Correct application of multiple testing methods in projects with several experiments

    Hi! I have a problem with evaluating how I should correct my alpha and conduct statistical texts when I have several different exeriments in the...

    Started by Szkeptik‎, 02-23-2017 04:32 AM
    anova, holm-bonferroni method, multiple testing
    • Replies: 1
    • Views: 917
    03-04-2017, 10:36 PM Go to last post
  46. Smile Comparative study

    Im doing comparative study of Kidney disease and Dermatoglyphics. There is a Continuous variable (ridge count) i am assessing Confounding factors is...

    Started by buddhikatbw‎, 03-03-2017 09:24 AM
    case control study
    • Replies: 2
    • Views: 702
    03-03-2017, 09:36 PM Go to last post
  47. matched pre-post survey analysis help

    I have matched pre-and post test data that evaluated our workshop participants using Likert-type items. Meaning, the same people were given the same...

    Started by hipstats‎, 02-28-2017 05:10 PM
    • Replies: 3
    • Views: 773
    03-03-2017, 08:52 AM Go to last post
  48. Test negative factors among correlated determinants

    Dear all, I am working on the obesity research. I found a molecule A that is negatively control the generation of adipocytes. I have a cohort of...

    Started by pinetop‎, 02-25-2017 12:05 AM
    correlation, negative, regression
    • Replies: 1
    • Views: 724
    03-02-2017, 01:41 PM Go to last post
  49. Cox regression to adjust for site effect in multicenter trial

    Hello All, Can stratified Cox regression be used to adjust for site effect in multicenter trials? Thank you in advance to all those who reply.

    Started by ineedhelpplease‎, 02-27-2017 10:44 PM
    • Replies: 3
    • Views: 1,174
    02-28-2017, 05:34 PM Go to last post
  50. Testing for trend

    I have following data that represent number of new patients with rare disease for subsequent 5 year time periods: 4, 3, 4, 2, 4, 2, 4, 6, 11 As I...

    Started by Markica85‎, 02-25-2017 09:25 AM
    • Replies: 12
    • Views: 1,636
    02-28-2017, 01:30 PM Go to last post
  51. Analysis of Repeated Measures Study with Unequal Time Between Measurements

    Hello Everyone, I have inherited the analysis of a study from a previous research student. I am having trouble determining what type of analysis...

    Started by rafreakijones‎, 02-10-2017 12:42 PM
    • Replies: 1
    • Views: 766
    02-24-2017, 09:56 PM Go to last post
  52. Statistical method to compare two experiments

    I have two data from biological experiment where two types of cells were measured. For each cell the data about composition of the membrane where...

    Started by magruc‎, 02-22-2017 04:23 AM
    • Replies: 1
    • Views: 719
    02-24-2017, 04:04 PM Go to last post
  53. Moran's I Spatial Autocorrelation. Interpreting results.

    I have carried out a Moran's I test on the residuals of a GLM model in the "ape" package in R which has returned the output below: Observed:...

    Started by avocadorose‎, 02-22-2017 02:16 PM
    glm, interpretation, spatial autocorrelation
    • Replies: 1
    • Views: 794
    02-23-2017, 06:40 AM Go to last post
  54. ADjusting for variables in regression model

    Dear all, I'm comparing two populations of oncologic patients that were treated with two different regimens in two different hospitals, group A of...

    Started by Markica85‎, 02-13-2017 06:43 AM
    • Replies: 6
    • Views: 1,286
    02-22-2017, 01:56 PM Go to last post
  55. Can I combine univariate and multivariate HR?

    Hi guys. I'm doing a meta-analysis of survival based on a blood marker, and not all the studies have provided a multivariate hazard ratio. Some have...

    Started by ngmowbray‎, 02-21-2017 07:38 AM
    medical statistics, meta analysis
    • Replies: 6
    • Views: 835
    02-21-2017, 09:08 PM Go to last post
  56. Categorical Variable with Repeated Data Points

    Hello, I have some data (continuous DV, nominal IV), that I would like to run an ANOVA or regression on. Strictly speaking, I have 3 levels, but...

    Started by StatsN00bie‎, 02-15-2017 03:22 PM
    • Replies: 1
    • Views: 948
    02-15-2017, 05:40 PM Go to last post
  57. Clinical decision interval

    Hi all, I have a question regarding clinical decision intervals (grey zone). We have developed a new screening test and we want to provide the...

    Started by Vbogaert‎, 02-08-2017 02:41 AM
    • Replies: 1
    • Views: 728
    02-13-2017, 08:24 AM Go to last post
  58. Assessing covariates to include in model

    Hi all, I have a couple of basic questions which would be great to get some help on I have a continuous outcome (brain volume: total and divided...

    Started by Alanine‎, 02-09-2017 10:47 AM
    • Replies: 2
    • Views: 846
    02-10-2017, 06:57 AM Go to last post
  59. Question [RNA-Seq] Sparse (discrete) p values with Cuffdiff

    Hello biostatisticians, I have run a very standard RNA-Seq protocol using TopHat - Cufflinks - Cuffmerge and Cuffdiff to measure differential gene...

    Started by FR_myologist‎, 02-08-2017 02:49 PM
    • Replies: 0
    • Views: 945
    02-08-2017, 02:49 PM Go to last post
  60. propensity matching and ITT for cohort study

    I am reviewing a cohort study that used a retrospective database to determine if treatment with hypothermia post cardiac arrest improves survival to...

    Started by Roundtoit‎, 02-06-2017 04:49 PM
    itt, propensity score matching, sensitivity analysis, survival analysis
    • Replies: 0
    • Views: 905
    02-06-2017, 04:49 PM Go to last post

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