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Forum: Biostatistics

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

  1. Question Multiple t-tests vs ANOVA with Dunnett's post-hoc test

    Hello, I am bit confused about the use of multiple t-tests vs ANOVA with Dunnett's post-hoc test (on normally distributed data). Let's take the...

    Started by Biochemist‎, 10-14-2017 07:46 AM
    • Replies: 2
    • Views: 118
    10-14-2017, 12:18 PM Go to last post
  2. Retrospective chart review subject selection: case vs. control

    I did retrospective chart review on 240 subjects from my previous institute. THe study was on sedation required for bronchoscopy. The procedure used...

    Started by dr_pritish‎, 10-14-2017 10:37 AM
    chart review
    • Replies: 0
    • Views: 66
    10-14-2017, 10:37 AM Go to last post
  3. RCT: estimation of total sample size knowing only the percentage of occurrence

    Dear all, I was asked to estimate the minimum sample size to set up a RCT comparing a standard dose technique to detect recurrence of disease vs...

    Started by MDaniele‎, 10-12-2017 04:31 AM
    estimate, noninferiority, rct, sample size, trial
    • Replies: 0
    • Views: 81
    10-12-2017, 04:31 AM Go to last post
  4. [SPSS - Mixed Models] Repeated measurements data from randomised controlled trial

    I am analyzing data from a randomized clinical trial, with 2 intervention groups (placebo and intervention) and repeated measurements over time. I am...

    Started by Flightpete‎, 10-05-2017 11:25 AM
    control for, mixed effects model, randomized control trials, spss
    • Replies: 2
    • Views: 167
    10-09-2017, 10:26 AM Go to last post
  5. Triangulating multiple data sources of prescription information

    I am currently working on a retrospective database study assessing the real-world effectiveness of a medication. I am faced with a few challenges. I...

    Started by vpmwar‎, 10-06-2017 11:59 AM
    agreement, cohens's kappa, correlation, triangulation
    • Replies: 0
    • Views: 145
    10-06-2017, 11:59 AM Go to last post
  6. Comparing the effectiveness of an intervention in two groups?

    Hi Everyone, I'm stuck trying to find a way to compare whether or not a given intervention has a greater effect in one group (Kids < 5) than...

    Started by jpgordon‎, 10-03-2017 10:29 PM
    • Replies: 1
    • Views: 114
    10-04-2017, 08:01 AM Go to last post
  7. Looking for a test to find if there is a relationship between 2 groups

    Hi all, I have a data set of two frequencies, one is the frequency of air temperature and the second is the frequency that an activity occurs at...

    Started by spulak‎, 10-02-2017 12:07 PM
    • Replies: 2
    • Views: 121
    10-02-2017, 03:37 PM Go to last post
  8. Block design anova

    I have a question about what the most appropriate anova design is for my data. I am posting here because I cannot seem to get the search function to...

    Started by vanguard605‎, 09-11-2017 03:52 PM
    anova, block design, community ecology
    • Replies: 2
    • Views: 336
    09-29-2017, 08:35 AM Go to last post
  9. Using logistic regression to compute age-adjusted rates

    Dear All, Would anybody please give me a breakdown no how to compute "age-adjusted proportions" based on the logistic regression coefficients? ...

    Started by Raok‎, 09-15-2017 06:53 AM
    • Replies: 4
    • Views: 439
    09-22-2017, 10:02 AM Go to last post
  10. Interpreting significance based on confidence interval

    Hi Everyone, Could some of you help to interpret my results based on p values and confidence intervals? A little bit of background: I am trying to...

    Started by julian_DE‎, 09-21-2017 07:48 AM
    • Replies: 3
    • Views: 238
    09-22-2017, 05:04 AM Go to last post
  11. Repeated measures with varying count between group

    I'll explain my problem a bit: I have two groups S(story) and P(picture). Each is composed of the same 48 subjects. My endpoint is a 'score' on an...

    Started by qjuice‎, 09-18-2017 06:46 PM
    • Replies: 5
    • Views: 287
    09-20-2017, 05:05 PM Go to last post
  12. Switch of distribution during observation period (Scratch Assay)

    Dear Stats-Talkers, I performed several Scratch Assays (its an experiment where cells close a cell-free gap over time, see also attached file I)...

    Started by Peters‎, 09-12-2017 04:00 AM
    • Replies: 0
    • Views: 253
    09-12-2017, 04:00 AM Go to last post
  13. Modeling and predicting pathology from multivariate clinical data

    Hello, I have a clinical data set that consists of 5 clinical measurements on thousands of tissue samples. Furthermore, each sample has a pathology...

    Started by jason.parker‎, 09-09-2017 04:50 PM
    biostats, cancer, prediction
    • Replies: 2
    • Views: 203
    09-11-2017, 09:55 AM Go to last post
  14. what statistical test to choose (large smple size)

    Hi all, I need to perform a test which shows if there is a statistical difference between males and females in getting diagnosis. I believe I should...

    Started by bburugap‎, 09-09-2017 08:34 PM
    • Replies: 2
    • Views: 235
    09-10-2017, 09:48 AM Go to last post
  15. Chi square p value <0.01 but graph pad prompts not valid

    Hello all, i have used graph pad prism to calculate p- value. my contingency table contains some observed frequencies which are 0. my p-value has...

    Started by Tiya‎, 09-09-2017 12:52 PM
    • Replies: 1
    • Views: 184
    09-09-2017, 01:09 PM Go to last post
  16. Poll Poll: Similarity instead of differences in means b/w 2 groups

    Hi - long time lurker. First time poster. I'm hoping folks can provide guidance and opinions. I am looking at a small pilot study (n=16) of...

    Started by drtoddchang‎, 08-28-2017 12:16 AM
    equivalence, heart rate, paired, wilcoxon signed
    • Replies: 4
    • Views: 403
    08-28-2017, 03:33 PM Go to last post
  17. Is Chi-square appropriate for a single measurement variable with repeated measures?

    Hi! I am looking at how many burrows are occupied by a skink species at eight sites across a property. Counts of the number of occupied burrows...

    Started by RustyEcologist‎, 08-22-2017 11:54 PM
    • Replies: 2
    • Views: 321
    08-24-2017, 06:20 PM Go to last post
  18. One way ANOVA vs Kruskal Wallis

    Hi, I am comparing four groups (measurements of bone thickness and other bone parameters). The distributions are normal (Kolmogorov–Smirnov test)...

    Started by n.lu‎, 08-23-2017 05:04 AM
    kruskal wallis, nonparametric, one way anova, parametric
    • Replies: 1
    • Views: 293
    08-23-2017, 08:38 AM Go to last post
  19. Question Can I calculate the % of people positive for an outcome from an odds ratio?

    Hi, Thanks for looking at my question. Background I am doing a systematic reveiw and metanalysis, essentially on diagnostic test accuracy and...

    Started by SSSA‎, 08-18-2017 10:09 AM
    odds ratio
    • Replies: 8
    • Views: 370
    08-21-2017, 02:45 AM Go to last post
  20. Cox Regression with missing values

    Very grateful for any advice. I'm trying to perform Cox regression on a data set with multiple random missing values. SPSS is my go-to software,...

    Started by Rowena‎, 08-13-2017 04:36 AM
    cox regression, missing values, sas, spss
    • Replies: 5
    • Views: 424
    08-17-2017, 05:06 AM Go to last post
  21. Best scenario: unpaired or paired situation?

    I have a few questions, but first let me give you some necessary background of the experiment and the underlying questions. Basically, the design...

    Started by tleal‎, 08-15-2017 11:37 AM
    hypothesis testing, matched, paired, pairing, unpaired
    • Replies: 0
    • Views: 220
    08-15-2017, 11:37 AM Go to last post
  22. Freidman test with missing values?

    I have a set of data at four time points, but some subjects only two out of the four time points. Can I still use Friedman test for this in SPSS?

    Started by zhu‎, 08-15-2017 11:34 AM
    • Replies: 0
    • Views: 132
    08-15-2017, 11:34 AM Go to last post
  23. Propensity Score Matching

    Hi! I'm conducting a retrospective study in which we want to analyze time period of 60 days before occurence of a particular adverse event. To do...

    Started by joanna513‎, 08-09-2017 07:06 AM
    propensity score matching
    • Replies: 1
    • Views: 309
    08-09-2017, 08:56 AM Go to last post
  24. 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: 6
    • Views: 894
    08-08-2017, 09:34 PM Go to last post
  25. 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: 7
    • Views: 859
    08-08-2017, 09:33 PM Go to last post
  26. Help with correct statistical analysis?

    I am conducting an audit into vitamin D deficiency in children. I have the mean serum concentrations of vitamin D in specific areas (postcodes)...

    Started by MedStudent‎, 07-03-2017 05:54 PM
    • Replies: 5
    • Views: 609
    08-08-2017, 09:32 PM Go to last post
  27. Statistical significance

    Hi, I have the following problem and I would need some piece of advice to solve it: I have a group of 28 patients (17 survived, 11 died) and I...

    Started by Carcassonne‎, 07-10-2017 02:51 AM
    • Replies: 8
    • Views: 630
    08-08-2017, 09:31 PM Go to last post
  28. Critiquing a Network Meta-analysis: Interpreting inconsistency

    Hi all. I'm a non-statistician trying to critique a network meta-analysis on a group of migraine medications called triptans (PDF link). The...

    Started by networkMA‎, 07-18-2017 02:18 PM
    • Replies: 3
    • Views: 368
    08-08-2017, 09:30 PM Go to last post
  29. Exclamation STATA Logistic Regression Intepretation

    Hi, My dependent variable is goes to college coded 0=No and 1= Yes. I am not sure how STATA reads/ranks the dependent variable....thus I am not...

    Started by I_AM_KB‎, 08-03-2017 02:53 PM
    interpreting odds ratios, logistic regression, stata
    • Replies: 0
    • Views: 311
    08-03-2017, 02:53 PM Go to last post
  30. Sphericity with unequal sample sizes

    Hello, I want to do a repeated measures anova in R on a data set consisting of four treatments on subjects, over 4 weeks. However, in week 3 I am...

    Started by Wouterka‎, 07-30-2017 11:21 AM
    • Replies: 0
    • Views: 304
    07-30-2017, 11:21 AM Go to last post
  31. Question Need Appropriate Test for comparing a series of measurements from one bone to another

    My research involves taking measurements at 9 sections at different locations on the shaft of bones. I am having trouble determining which...

    Started by SierraS‎, 07-13-2017 11:58 PM
    bone, pair, series, test
    • Replies: 2
    • Views: 472
    07-23-2017, 08:41 PM Go to last post
  32. Online Biostatistics Course/Master's Degree

    Hi everyone, I'll be glad if someone could recommend me some online Biostatistics Course or Master's Degree for beginner. Thanks!

    Started by ovallecc‎, 07-20-2017 03:07 AM
    • Replies: 1
    • Views: 475
    07-20-2017, 04:23 AM Go to last post
  33. Patient-year Incidence rates comparisons and p value

    Dear all, I would like to statistically compare two incidence rates from two different groupes. I found the Incidence rate difference (IRD)...

    Started by didye‎, 07-19-2017 04:43 AM
    compare rates, incidence rate, ird
    • Replies: 0
    • Views: 320
    07-19-2017, 04:43 AM Go to last post
  34. Help with comparing disease death rates over time

    Hello everyone, I am working with a national mortality file and have pulled certain deaths for a particular disease and created crude rates by...

    Started by LAM_13‎, 07-17-2017 07:03 PM
    • Replies: 0
    • Views: 662
    07-17-2017, 07:03 PM Go to last post
  35. Software for NHANES Analysis

    Hello! I'm going to be using NHANES data for some of my research looking at dietary factors and health-related outcomes. I have a bit of exposure to...

    Started by mam326‎, 07-14-2017 04:25 PM
    • Replies: 0
    • Views: 354
    07-14-2017, 04:25 PM Go to last post
  36. Multi-level Meta-regression using random effect for treatment? [R pkg metafor]

    I am a biostatistician consulting on a meta-analysis of 16 studies each w/ 2 treatment arms. The main interest is in the effect of the variable...

    Started by chelbylu‎, 07-06-2017 03:45 AM
    hierarchical model, meta-regression, r metafor, random effects, treatment
    • Replies: 0
    • Views: 439
    07-06-2017, 03:45 AM Go to last post
  37. Help choosing right statistics

    The experiment consisted of testing the effect of several diets on the weight of fish. I want to check what groups differ from each other. There is...

    Started by Andre Barreto‎, 06-26-2017 02:58 PM
    • Replies: 2
    • Views: 582
    06-26-2017, 04:06 PM Go to last post
  38. 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: 1,112
    06-08-2017, 10:58 AM Go to last post
  39. 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: 986
    06-04-2017, 03:02 PM Go to last post
  40. 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: 1,236
    05-30-2017, 03:48 PM Go to last post
  41. 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: 701
    05-30-2017, 08:46 AM Go to last post
  42. 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: 787
    05-26-2017, 08:36 AM Go to last post
  43. 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: 1,285
    05-22-2017, 09:28 AM Go to last post
  44. 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: 1,053
    05-15-2017, 08:55 PM Go to last post
  45. 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: 809
    05-15-2017, 08:24 AM Go to last post
  46. 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: 734
    05-12-2017, 12:15 PM Go to last post
  47. 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: 1,689
    05-07-2017, 03:06 AM Go to last post
  48. 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: 782
    05-06-2017, 11:02 PM Go to last post
  49. 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: 1,489
    05-04-2017, 05:59 PM Go to last post
  50. 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: 964
    05-01-2017, 04:23 AM Go to last post
  51. 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: 1,035
    04-27-2017, 02:59 PM Go to last post
  52. 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: 955
    04-27-2017, 01:02 PM Go to last post
  53. 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: 1,034
    04-24-2017, 02:15 PM Go to last post
  54. 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: 1,277
    04-20-2017, 08:16 AM Go to last post
  55. 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: 1,522
    04-16-2017, 08:32 AM Go to last post
  56. 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: 746
    04-15-2017, 11:04 AM Go to last post
  57. 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: 1,210
    04-13-2017, 09:29 AM Go to last post
  58. 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: 929
    04-10-2017, 04:57 PM Go to last post
  59. 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: 1,102
    04-07-2017, 02:08 PM Go to last post
  60. 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: 1,112
    04-05-2017, 04:04 PM Go to last post

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