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Forum: Biostatistics

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

  1. Point Prevalence over 5 years when only given data for 1 year

    Hi all, I'm abit confused about a tricky sort of Prevalence calculation. So here's my problem- Sample of 500 people. In 1 year 5...

    Started by Rekansha‎, 04-16-2014 05:56 AM
    point prevalence, prevalence incidence
    • Replies: 0
    • Views: 1,990
    04-16-2014, 05:56 AM Go to last post
  2. Survival Analysis with Interval Censored Data

    Dear All I'm trying to do a survival analysis with interval censored data. The data are basically eye pressure measurements at certain...

    Started by SiBorg‎, 03-05-2012 12:37 PM
    • Replies: 13
    • Views: 11,647
    04-15-2014, 03:06 AM Go to last post
  3. considering covariates in a non parametric test

    Hello, I have the following problem: I have to analyze two variables, both continuous (they are results of body tests). Since I have cases only...

    Started by Rerun‎, 04-12-2014 05:38 AM
    • Replies: 4
    • Views: 2,885
    04-12-2014, 12:30 PM Go to last post
  4. Question Appropiate test/s for bounded data sets?

    Hello! I am comparing between groups of data that have both lower and upper bounds. Most of the time my data sets qualify as being normally...

    Started by phaynes‎, 04-10-2014 07:10 PM
    bounded, different distributions
    • Replies: 3
    • Views: 3,011
    04-11-2014, 12:34 PM Go to last post
  5. Repeated measures ANOVA - appropriate test?

    Hi - I'm working on data from a psychophiscs experiment. Briefly I have 10 participants, 3 conditions, and >100 trials for each participant-condition...

    Started by Qroid_mtl‎, 04-08-2014 01:14 PM
    • Replies: 3
    • Views: 1,844
    04-10-2014, 03:25 PM Go to last post
  6. Restructuring data

    Hey- I have data from a group of people, there was a baseline survey and then daily questions they filled out. While the participant ID is...

    Started by ros5291‎, 04-10-2014 02:04 PM
    restrucutre, transpose
    • Replies: 0
    • Views: 1,245
    04-10-2014, 02:04 PM Go to last post
  7. Appropriate test for two variables

    Hello, This is my first time posting here, so forgive me if I don't include something. I will follow this post and add more information as needed....

    Started by Crimsin23‎, 04-10-2014 09:17 AM
    biostats, compare groups, comparing, dependant samples
    • Replies: 0
    • Views: 1,856
    04-10-2014, 09:17 AM Go to last post
  8. How do I calculate time dependent covariates in SPSS?

    I am new to survival analysis and would appreciate some help! (I'm from psychology, and my discipline does not tend to conduct survival analysis) ...

    Started by jcfrqhr‎, 04-09-2014 04:11 PM
    cox regression, extended cox model, survival analysis, time dependence
    • Replies: 0
    • Views: 5,366
    04-09-2014, 04:11 PM Go to last post
  9. Cox Regression Output: SPSS vs R Question

    I have question for those more familiar with statistics. I’m a lab geek, so I have functional knowledge of these stats, but when things start getting...

    Started by ProSubzero‎, 04-09-2014 03:13 PM
    • Replies: 0
    • Views: 2,310
    04-09-2014, 03:13 PM Go to last post
  10. Sample size calculation; negative binomial distribution

    I am interested in doing a sample size calculation for exacerbation rates. I am drawing my data from a negative binomial distribution and my test...

    Started by biobee‎, 04-07-2014 08:37 PM
    • Replies: 5
    • Views: 7,609
    04-08-2014, 07:33 PM Go to last post
  11. R-Survival Analysis Interpretation of Coefficients

    Hi, I was wondering if anyone could help me on how to interpret the coefficient from an analysis I have carried out in R(survival library). ...

    Started by GH_F‎, 04-08-2014 06:57 AM
    • Replies: 2
    • Views: 2,166
    04-08-2014, 08:49 AM Go to last post
  12. Modelling this non-linear relationship- please help

    Hi All, I'm using usual Cox regression where my outcome is time to a binary event. My variable of interest (a biological marker) appears to show a...

    Started by ACA‎, 04-07-2014 08:17 PM
    cox regression, non-linear relationship, quadratic, survival analysis
    • Replies: 0
    • Views: 1,739
    04-07-2014, 08:17 PM Go to last post
  13. Help deciding what stats to run in SAS to determine effect of Obs bias on Group Size

    Hello, I'm trying to determine if the observer group size of a study ( 1, 2, 3) and experience of the observer impacts the potential for observer...

    Started by compassion83‎, 04-05-2014 06:11 PM
    anova, observer bias, sas
    • Replies: 0
    • Views: 1,366
    04-05-2014, 06:11 PM Go to last post
  14. Is ARIMA model appropriate for this dental research?

    Hi members. Please, I have a doubt in my study for doctoral thesis… Title: “Development of a thermal cycling protocol for dental materials”....

    Started by iivanchuk‎, 04-03-2014 03:20 PM
    arima, biostatistics, dental
    • Replies: 7
    • Views: 2,255
    04-04-2014, 04:43 PM Go to last post
  15. How to treat a Poisson generalized linear model when one treatment group is all zeros

    I'm using a Poisson generalized linear model (log link function) to model count data with one continuous and one categorical predictor. For one of...

    Started by Carabiniero‎, 03-19-2014 06:48 PM
    • Replies: 7
    • Views: 2,444
    04-03-2014, 11:13 PM Go to last post
  16. Help with data analysis aspect of study design.

    Dear Group, I am starting a PhD, its of the 'build your own' variety, i.e. its initiated by myself and not part of an existing project. I’m...

    Started by Morganb4‎, 03-31-2014 11:43 PM
    • Replies: 0
    • Views: 1,570
    03-31-2014, 11:43 PM Go to last post
  17. What is the appropriate R tests for studying drug effect under factors disruption?

    Hello biostat world I have a population of 35 mice, 17 are wild type and 18 are treated with drug. I sampled(12 biological replicate) all mice...

    Started by Bioinfo‎, 03-28-2014 11:52 AM
    combined anova, glmm, wilcox
    • Replies: 0
    • Views: 1,595
    03-28-2014, 11:52 AM Go to last post
  18. Weighting adjusted rates

    Hi All, I have a patient database with columns for observed and expected values for a number of outcomes. The observed values are binary, expected...

    Started by j00sel00se‎, 03-28-2014 08:53 AM
    • Replies: 1
    • Views: 1,847
    03-28-2014, 08:57 AM Go to last post
  19. Comparing school grades in a population against mean score in the gen. population

    First of all, I am not very proficient with statistics, but I am writing on a school project, and I would really appreciate some ideas on which...

    Started by levolac‎, 03-24-2014 02:06 PM
    • Replies: 4
    • Views: 1,687
    03-27-2014, 09:19 AM Go to last post
  20. Is Kaplan-Meier Log-rank p-value valid even if one group has zero events

    Hi all, So first off, I am a novice so I apologize if this is a beginner question. I am doing a research project where I am looking at immune...

    Started by DrK‎, 03-26-2014 11:25 PM
    kaplan-meier, log-rank
    • Replies: 0
    • Views: 2,774
    03-26-2014, 11:25 PM Go to last post
  21. Smile SEM identification question

    For the identification of P(Y=y|do(X=x)), one can condition on a set which has no descendants of X and d-separates all back-door paths. What would be...

    Started by azaleah‎, 03-25-2014 11:24 PM
    identification, sem
    • Replies: 2
    • Views: 1,771
    03-26-2014, 04:57 PM Go to last post
  22. Cross sectional study- how to treat multiple samples from same patient?

    Hey there, I know nothing about stats, but am hoping there is a simple answer to this problem. I am doing a study looking at different immune...

    Started by BioMel‎, 03-24-2014 08:39 AM
    • Replies: 3
    • Views: 2,075
    03-25-2014, 12:27 PM Go to last post
  23. Experimental design help: powering clinical study

    Hello, I am applying for an IRB to evaluate the effect of lidocaine (local anesthetic) dilution on pain and duration of intradermal anesthesia. ...

    Started by randallgunther‎, 03-17-2014 11:02 AM
    • Replies: 1
    • Views: 1,435
    03-25-2014, 02:59 AM Go to last post
  24. Estimating a proportion from a GEE model or GLMM model

    Hello all, I had a single sample of a binary outcome (success / failure), and I wanted to estimate the population proportion with a point estimate...

    Started by NN_STAT‎, 03-23-2014 08:45 AM
    • Replies: 1
    • Views: 2,856
    03-25-2014, 02:50 AM Go to last post
  25. Comparing community structure between sites

    Hi there, I am doing my PhD in Biogeochemistry and want to compare the relative distributions of certain lipids in environmental samples among...

    Started by yuki81‎, 03-22-2014 05:56 AM
    • Replies: 0
    • Views: 1,528
    03-22-2014, 05:56 AM Go to last post
  26. please help me

    what's the motivation for this study multinomial logistic regression

    Started by vip_un‎, 03-19-2014 05:00 PM
    • Replies: 5
    • Views: 1,723
    03-19-2014, 06:55 PM Go to last post
  27. Simultaneous application of complex survey weights and model weights

    Hello, I am trying to discern if and how to estimate a model that simultaneously applies weights for complex survey design and time-varying...

    Started by phgeojamie‎, 03-18-2014 11:14 PM
    complex design, propensity scores, survey weights
    • Replies: 0
    • Views: 1,497
    03-18-2014, 11:14 PM Go to last post
  28. overall model fit for generalized structural equation model

    Hi All, I'm new to this forum, and I hope I can be both of help and find help. My current problem involves modeling longitudinal data. I have...

    Started by nlink222‎, 03-18-2014 05:37 PM
    longitudinal data, model fit, stata 12, structural equation model
    • Replies: 0
    • Views: 4,974
    03-18-2014, 05:37 PM Go to last post
  29. Paired longitudinal analysis

    Hello all, I need your advice. I am examining an new eye drops. In order to examine, an experiment was performed, in which a subject was...

    Started by NN_STAT‎, 03-13-2014 03:38 PM
    clinical study, prospective study
    • Replies: 1
    • Views: 2,351
    03-15-2014, 10:54 PM Go to last post
  30. Experimental design help. Randomsied block and power analysis help

    All good, sorted it out :)

    Started by jcs1086‎, 03-14-2014 02:41 AM
    • Replies: 0
    • Views: 1,232
    03-14-2014, 02:41 AM Go to last post
  31. Smile can you help me ?

    what are the methods to estimate parameter in multinomial logistic regression? thanks

    Started by vip_un‎, 03-09-2014 04:16 PM
    • Replies: 6
    • Views: 2,232
    03-11-2014, 03:55 PM Go to last post
  32. STATA or SAS? Which one should I learn?

    Hello I am currently trying to go a little beyond SPSS by learning either SAS or STATA. My field is psychology and biostatistics. Which one of these...

    Started by sampier85‎, 01-07-2013 04:07 PM
    2 Pages
    1 2
    • Replies: 17
    • Views: 28,321
    03-11-2014, 11:50 AM Go to last post
  33. Is this really simple randomization for RCT?

    I had a debate with my friend over her study. She did a 2-arm ("A" for intervention and "B" for control) randomized controlled trial on 50 diabetic...

    Started by ttc‎, 03-10-2014 09:52 PM
    • Replies: 3
    • Views: 3,146
    03-11-2014, 07:25 AM Go to last post
  34. Unpaired repeated measures test?

    My dataset is pre- and post-test Likert Scale around an intervention, but it is not matched: it is collected anonymously from the same cohort of...

    Started by LivinginMaine‎, 12-13-2011 11:29 AM
    likert scale, repeated measures, unpaired
    • Replies: 7
    • Views: 7,249
    03-11-2014, 06:56 AM Go to last post
  35. outliers in survival probability

    Hi all, We use survival data of 90 patients that were divided in two sub groups. (31, 59). Two patients (out of the 31 sub group) survived 50%...

    Started by orb‎, 03-08-2014 08:41 AM
    outliers, survival analysis
    • Replies: 2
    • Views: 2,567
    03-09-2014, 06:28 PM Go to last post
  36. Extremely unequal samples sizes for Welch t-test

    Hi folks, I am currently comparing some gene expression results from tumor and normal cases and would like to determine for a small number of...

    Started by Igoor‎, 06-25-2013 03:01 AM
    • Replies: 5
    • Views: 9,721
    03-07-2014, 11:54 AM Go to last post
  37. Which model to use ?

    Hello, I have a data coming from the ophthalmology field, i.e, eyes. For each patient, an intervention is made on one eye (either left or...

    Started by NN_STAT‎, 03-03-2014 03:47 AM
    • Replies: 3
    • Views: 1,726
    03-04-2014, 07:46 AM Go to last post
  38. Post hoc for multivariate analysis with large number of dependent variables?

    Hello All, Basically, the study is looking at if forefoot striking (FFS) and rear foot striking (RFS) runners experience similar changes when...

    Started by missy_thompson‎, 03-03-2014 07:20 AM
    • Replies: 0
    • Views: 1,594
    03-03-2014, 07:20 AM Go to last post
  39. Survival analysis - two different end of study times

    Hi I am analysing time to event data using Cox Regression (SPSS) as there are a number of covariates to be included. Previously, the end of...

    Started by esnut‎, 02-12-2014 04:29 AM
    survival, time lag
    • Replies: 7
    • Views: 1,802
    03-03-2014, 03:05 AM Go to last post
  40. Urgent help: qusi-experimental analysis

    Hi, I am working on a quasi-experimental study, with an intervention to reduce HIV stigma. A score has been constructed (scale 0-10) to measure...

    Started by omarokasha‎, 02-26-2014 07:25 AM
    • Replies: 2
    • Views: 2,088
    03-02-2014, 03:19 AM Go to last post
  41. Minimal set of new predictor variable(s) and added value to existing predictor

    Hi everyone, I am working on gene expression data for 15 genes and am supposed to derive a minimal predictive set of genes that can be used as a...

    Started by bontus‎, 02-27-2014 04:00 PM
    added value, minimal set, predictor, stepwise
    • Replies: 0
    • Views: 1,281
    02-27-2014, 04:00 PM Go to last post
  42. Permutation Testing to find significant molecules

    Apologies if this is quite a basic question but I'm fairly new to stats. I have a 24 x 70 matrix consisting of rows of 24 human serum samples and...

    Started by Sheddie‎, 02-25-2014 02:58 PM
    permutation testing, statistics, t test
    • Replies: 0
    • Views: 1,661
    02-25-2014, 02:58 PM Go to last post
  43. Analyzing percentage data that clusters around 100%

    I have data from 10 mice looking at the percentage of a time period that each subject spent immobile before and after various drugs. I want to be...

    Started by hsmcc36‎, 02-25-2014 11:21 AM
    • Replies: 0
    • Views: 1,165
    02-25-2014, 11:21 AM Go to last post
  44. which statistical test shall I use?

    Hello, I have some doubts about which statistical test shall I use in this case. summarizing: my main variable of interest is the blood level of a...

    Started by Rerun‎, 02-24-2014 04:25 PM
    • Replies: 6
    • Views: 2,962
    02-25-2014, 06:11 AM Go to last post
  45. Meaning of significant interaction in repeated measures ANOVA - larval survival

    Hello, My research looks at the effects of ocean acidification on the larval development of crab larvae. I experimentally subjected crab larvae to...

    Started by Raphaelle‎, 02-24-2014 02:10 PM
    • Replies: 0
    • Views: 1,814
    02-24-2014, 02:10 PM Go to last post
  46. Want to run zero inflated regression... but my dependent variable is continous

    So I have been investigating the best model to run for my data. I originally looked at the zero inflated Poisson regression, but looked at my...

    Started by zombie_kid‎, 02-17-2014 11:29 PM
    • Replies: 14
    • Views: 2,925
    02-22-2014, 10:38 PM Go to last post
  47. MANOVA searching for consistency across sites

    Dear All, I would like to ask you what do you think of using MANOVA with my dataset to search for consistency (or lack of consistency) across...

    Started by panas‎, 02-21-2014 05:05 AM
    • Replies: 0
    • Views: 1,839
    02-21-2014, 05:05 AM Go to last post
  48. Nested Mixed Model - SPSS - Have I defined my terms correctly?

    I am trying to do a nested repeated measures mixed model. My design is very messy, has small sample size, and is unbalanced. I am trying to figure...

    Started by Andrea‎, 02-20-2014 05:15 PM
    • Replies: 0
    • Views: 2,355
    02-20-2014, 05:15 PM Go to last post
  49. Question How to best combine 3 repeated experiments

    Hi there, I would appreciate some expert advice on how to best combine 3 replicated experiments into one analysis. I’m trying to check if a...

    Started by luka158‎, 02-20-2014 08:37 AM
    combine, glm, repeated experiments
    • Replies: 0
    • Views: 2,370
    02-20-2014, 08:37 AM Go to last post
  50. P-values for leave-one-out accuracy (on imbalanced label set)

    Dear board members, I am happy to have found this very nice community :-) I have a question and I hope that someone can help me. I want to...

    Started by polynom‎, 02-19-2014 01:22 PM
    • Replies: 0
    • Views: 1,458
    02-19-2014, 01:22 PM Go to last post
  51. What model should I use? Studbook data

    Hi all, I use R and want to analyze a dataset from a studbook that contains information of populations of the same species on different locations....

    Started by Carmenvdb‎, 02-18-2014 12:13 PM
    fecundity, model, rstatistics, studbook, survivorship
    • Replies: 0
    • Views: 1,309
    02-18-2014, 12:13 PM Go to last post
  52. Confounding in Multivariate Linear Regression

    Hi all, I'm using SPSS to analyse my research data. Usally i'm building logistic regressions in which I find confounders by noticing a change...

    Started by BGUer‎, 02-18-2014 05:23 AM
    counfounding.linear model
    • Replies: 0
    • Views: 2,583
    02-18-2014, 05:23 AM Go to last post
  53. Choice of test for detecting difference in methods for estimating muscle attachment

    In my line of research, we are interested in determining how muscles drive body movements. To do so, we need to know where muscles attach on the...

    Started by stoig_attacks‎, 02-16-2014 11:26 AM
    • Replies: 0
    • Views: 1,161
    02-16-2014, 11:26 AM Go to last post
  54. Confused ! help !

    Hello. I am doing a dissertation on the epidemiology of Parkinson's disease in a district where I need to calculate the age-specific incidence rate...

    Started by cacpaizon‎, 02-15-2014 06:19 AM
    • Replies: 0
    • Views: 1,051
    02-15-2014, 06:19 AM Go to last post
  55. Choice of Test for research data in Femur bone fracture analysis.

    Hello , I am Using SPSS on Windows 8 and SPSS Version 20. I have data regarding the Femur bone fracture strength on patients with Hip and knee...

    Started by AbhishekSPSS‎, 02-08-2014 07:10 AM
    • Replies: 4
    • Views: 1,957
    02-11-2014, 08:48 AM Go to last post
  56. Confused with meta-analysis (Hedges); credibility intervals

    Dear All, Many thanks in advance for reading this - any help is gratefully received! I'm trying to combine the incidence rates for a...

    Started by RDF‎, 02-11-2014 06:29 AM
    confidence interval, incidence rate, meta analysis
    • Replies: 0
    • Views: 2,435
    02-11-2014, 06:29 AM Go to last post
  57. Accounting for random effects from sampled individuals in GLM

    Hello, this is my first post but I am sure it won't be my last. I am working on my thesis and just sent the first round of analyses to my committee....

    Started by zombie_kid‎, 02-04-2014 09:32 PM
    • Replies: 11
    • Views: 2,255
    02-06-2014, 01:37 PM Go to last post
  58. Logistic regression analysis and quantitative discrete variables

    Maybe I should start this post explaining that I am a physician working in the public health system in Brazil with little knowledge about the subject...

    Started by Acenes‎, 01-19-2014 12:49 PM
    • Replies: 4
    • Views: 3,792
    02-05-2014, 07:58 AM Go to last post
  59. COX PH model and Weibull regression model plots

    Hi, I need to form plots comparing values that are fitted to COX model to same values fitted to Weibull regression model using R. Can anyone...

    Started by itamarg‎, 02-04-2014 12:52 PM
    • Replies: 0
    • Views: 2,428
    02-04-2014, 12:52 PM Go to last post
  60. Unsure Which Test to Use

    Hi, We are doing some experiments in which we are poking holes of various diameters using needles (the intervals are inconsistent - 2.1 mm, 1.3...

    Started by vigneshr11‎, 01-31-2014 05:12 PM
    • Replies: 2
    • Views: 2,010
    02-03-2014, 08:09 PM Go to last post

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