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Forum: Biostatistics

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

  1. Study Design for assessing New Clinical Sign where gold standard is not available

    Hi! I am looking for some guidance as to what statistical tests I would need to do to know the significance of a study. The situation is this: ...

    Started by cielo‎, 01-02-2016 09:54 AM
    • Replies: 1
    • Views: 1,162
    01-02-2016, 11:08 AM Go to last post
  2. Site x species matrix and enviromental Variables. Which tests should I use

    Hello Talkstats Forum, I am currently doing my study with the theme: Effects of farming type and landscape density on carabid diversity and...

    Started by Carabid‎, 12-19-2015 06:34 AM
    cca, dca, environment variables, species data
    • Replies: 1
    • Views: 1,564
    12-22-2015, 12:07 PM Go to last post
  3. MaxT corrected p value

    Hi all, I am trying to permute data and return a maxT p value to adjust for FWER. I have an example of data: SNP1 p value= 0.02 SNP1...

    Started by Evied‎, 12-22-2015 08:22 AM
    maxt, p value, permutation
    • Replies: 0
    • Views: 839
    12-22-2015, 08:22 AM Go to last post
  4. Inquiry about means comparision of factorial experiments

    urgent and important dear, friends I need clarification about comparison between interaction of treatments. If I've factorial experiment (2*3) with...

    Started by hazemalashwal‎, 12-21-2015 10:12 AM
    • Replies: 0
    • Views: 973
    12-21-2015, 10:12 AM Go to last post
  5. Exclamation Help with Biostats Hw question

    The research team has considered your answers to the above. They’ve narrowed their interest to two outcomes (for now): Number of episodes of early...

    Started by 303oselim‎, 12-18-2015 08:00 PM
    biostats, stats
    • Replies: 0
    • Views: 1,227
    12-18-2015, 08:00 PM Go to last post
  6. Need help choosing a statistical method/model

    Hello, I am currently doing a study on the defensive behavior of the European Grass Snake, and I was hoping someone could help me figure out...

    Started by brittany‎, 06-23-2015 09:44 AM
    anova ecology biology, help!, linear mixed model, logistic regression, nested anova
    • Replies: 2
    • Views: 1,233
    12-18-2015, 07:29 PM Go to last post
  7. Trying to analyze aggregated data

    Hi, I would like to know how it would be possible to make a t-test with aggregated data on SPSS or R. My dataset looks like this: ...

    Started by Sarou‎, 12-17-2015 12:14 PM
    aggregated data, biostatistics, spss, t-tests
    • Replies: 3
    • Views: 1,718
    12-17-2015, 03:57 PM Go to last post
  8. Agreement between raters who record the frequency at which they would choose options

    Say I have 5 raters and 6 choices. For each choice, each rater records a frequency from 0 to 100: the percentage of time they would choose that...

    Started by emogene‎, 12-17-2015 10:01 AM
    • Replies: 0
    • Views: 907
    12-17-2015, 10:01 AM Go to last post
  9. what is the objective of yeast dataset?

    Recently, l started working on yeast data (http://archive.ics.uci.edu/ml/datasets/Yeast). My goal is to do an exploratory statistics upon these data,...

    Started by montecarlo‎, 12-16-2015 06:54 AM
    data analysis, pca analysis, statistical analysis
    • Replies: 1
    • Views: 1,059
    12-16-2015, 05:13 PM Go to last post
  10. What method shpuld i use?

    i'm confuse how to analyze my data. 1. i have 2 independent factor and 4 dependent factor, with unexpected count high to 75%, what analytical method...

    Started by Denxe‎, 12-16-2015 10:18 AM
    • Replies: 0
    • Views: 1,167
    12-16-2015, 10:18 AM Go to last post
  11. Checking my approach - Mann whitney

    Hi everyone I was wondering if I had used the correct approach to analyse my data. I have four groups of people answering a survey and taking part...

    Started by Statistics help‎, 12-14-2015 05:51 AM
    kruskall-wallis, mann whitney u test
    • Replies: 2
    • Views: 1,275
    12-15-2015, 05:16 PM Go to last post
  12. Analyzing dataset with zeros

    I am analyzing a dataset on offspring production in fruit flies that have mated with individuals from their own population or another population. So...

    Started by Jbon‎, 12-03-2015 12:20 PM
    • Replies: 5
    • Views: 2,306
    12-14-2015, 09:07 AM Go to last post
  13. GLMM versus logistic regression if no random effects

    Dear all, I am working with binary data and I was wondering: in a model that does not include any random effect (only fixed effect), ...

    Started by nicoladiggi‎, 12-13-2015 05:46 AM
    • Replies: 5
    • Views: 2,030
    12-13-2015, 06:09 PM Go to last post
  14. Post Which statistical test?

    Hey there, I have an experiment involving 2 groups of people: a control and a test. There were 30 different people in each group and the test group...

    Started by AC82‎, 12-12-2015 10:36 AM
    which statistical
    • Replies: 0
    • Views: 1,004
    12-12-2015, 10:36 AM Go to last post
  15. Does this graph shows a normal distribution ?

    Hello, I am a newbie in Biostatistics field... I would be so thankful if you tell me if below chart has a normal distribution or not and why ? ...

    Started by A.Chakery‎, 11-21-2015 03:16 PM
    • Replies: 4
    • Views: 1,492
    12-10-2015, 11:32 AM Go to last post
  16. Question Funnel plot - is the funnel overlay just a visual tool or is it precisely calculated?

    I'm trying to create a funnel plot, and I'm wondering if there's a rule behind the funnel shape - are the two slanted lines simply meant to cross the...

    Started by j4ne‎, 12-10-2015 06:16 AM
    • Replies: 1
    • Views: 1,312
    12-10-2015, 09:12 AM Go to last post
  17. Direct standardization - age

    Hi I have data with 250 events during an 10-year period. I have calculated incidence rates based on the general population. I now want to...

    Started by Laurjo‎, 12-10-2015 04:47 AM
    age groups, standardization, strata
    • Replies: 0
    • Views: 930
    12-10-2015, 04:47 AM Go to last post
  18. Red face Help with Cox Regression

    Hi all, it's my first time here, but I hope to be able to contribute to other threads soon. I'm working on a dataset at the moment, and need a...

    Started by researchworker‎, 12-08-2015 10:10 AM
    • Replies: 10
    • Views: 1,584
    12-09-2015, 03:49 PM Go to last post
  19. Which statistical test would you suggest in this case?

    Hello to everyone, I have a question on how to choose the best statistical test to see whether what I have found is significant or not. That is...

    Started by Alessiaa‎, 12-09-2015 11:55 AM
    • Replies: 0
    • Views: 902
    12-09-2015, 11:55 AM Go to last post
  20. Test for healthy and sick organ development

    Hi guys, Quick question: I have data from patients who suffer on some organ failure. Let’s say I have ten organ function measurements over time....

    Started by Stats_Newbie‎, 12-02-2015 10:57 AM
    • Replies: 3
    • Views: 1,328
    12-05-2015, 02:51 PM Go to last post
  21. Need Help: Kaplan Meier analysis

    Hi I have a large database and have generated KP curves for long term survival but there is not difference in overall/long term survival. Our goal...

    Started by survivinganalysis‎, 11-28-2015 12:07 AM
    • Replies: 1
    • Views: 881
    11-28-2015, 02:56 AM Go to last post
  22. Appropriate p-value correction in two cohort meta-analysis (discovery / validation)

    Dear all, I would like to request your help and opinions on a meta-analysis setup utilizing two completely independent cancer cohorts, where one...

    Started by bontus‎, 11-26-2015 10:31 AM
    dataset integration, fdr, meta analysis, p-value correction, validation
    • Replies: 0
    • Views: 989
    11-26-2015, 10:31 AM Go to last post
  23. Analysis for progression free survival (PFS), and Dose intensities effect on PFS.

    Hi every Body, The project that we are doing is related to a drug that is given to patients having colorectal cancer, after they have failed all...

    Started by sanaullah92‎, 11-18-2015 08:11 PM
    progression free survival
    • Replies: 0
    • Views: 968
    11-18-2015, 08:11 PM Go to last post
  24. Spearman partial correlation corrected for multiple comparisons

    Hi all, I would like to ask you some help about this: Which would be the Bonferroni correction for a Spearman partial correlation controlled by...

    Started by purkinje‎, 11-17-2015 10:27 AM
    spearman bonferroni
    • Replies: 0
    • Views: 1,174
    11-17-2015, 10:27 AM Go to last post
  25. Data Analysis for Clinical Trials

    For a research module, for my postgraduate degree, I need to design a clinical trial research protocol. I am looking at how safe and effective drug X...

    Started by Joseph551‎, 11-15-2015 02:03 PM
    • Replies: 3
    • Views: 1,623
    11-16-2015, 03:28 PM Go to last post
  26. Help concerning random forest in R

    Working on a data set with bio markers. This is a classification problem and I'm having some troubles finding any information concerning the process...

    Started by lukketotte‎, 11-16-2015 10:43 AM
    • Replies: 0
    • Views: 733
    11-16-2015, 10:43 AM Go to last post
  27. Need help with spline for clustered data

    Hello everyone, I am a new member on this forum. I am recently running into a problem with analyzing correlated data for a twin study. I am...

    Started by Tiny‎, 11-10-2015 07:19 AM
    • Replies: 0
    • Views: 1,436
    11-10-2015, 07:19 AM Go to last post
  28. Multiple groups, comparing healthcare costs, problem: excluding specific data [Prism]

    Hi I have cost data for three groups of patients and we want to see if there is a difference in costs before, during and after we implemented a...

    Started by moeveleigh‎, 11-08-2015 08:42 AM
    • Replies: 0
    • Views: 886
    11-08-2015, 08:42 AM Go to last post
  29. Treatment-experiment interactions in multivariate data

    I have a data set of multivariate data (4 treatments, 3 samples per treatment, 14 variables, the variables are concentrations of different...

    Started by Tabita‎, 11-06-2015 04:26 AM
    f-test, multivariate analysis, multivariate data, repeated experiments
    • Replies: 0
    • Views: 1,000
    11-06-2015, 04:26 AM Go to last post
  30. I need help to analyze this data

    Dear valued experts, I need help in calculating the significance of the following data: Two groups of patients on Rx (A) and (B) I am comparing...

    Started by farahi‎, 11-04-2015 06:35 AM
    • Replies: 0
    • Views: 918
    11-04-2015, 06:35 AM Go to last post
  31. Help! Nursing statistics- wordy problem no one in the class can answer

    Hi everyone! Hoping someone is able to help guide me and my classmates. Our teacher isn't great and will not assist us with this question. Our...

    Started by nursestatsdummy‎, 10-30-2015 11:03 PM
    • Replies: 1
    • Views: 1,410
    10-30-2015, 11:34 PM Go to last post
  32. What test to run ?

    Hi everybody! I have a small sample of patients that have undergone two interventions and we want to analyze the effect on a specific bloodsample...

    Started by Cak024‎, 10-29-2015 07:25 AM
    • Replies: 0
    • Views: 649
    10-29-2015, 07:25 AM Go to last post
  33. Sample size

    Hello! I need your help to define the sample size of a study. We want to study the effect of a food on the expression of a series of microRNAs...

    Started by Fischer‎, 10-28-2015 07:12 AM
    • Replies: 2
    • Views: 1,438
    10-29-2015, 04:20 AM Go to last post
  34. Question Pearson's Correlation _ with individual X error and Y error

    Hi all, I have a problem that I can't seem to solve. I don't know how to account for the individual measurement error in a Pearson's correlation r...

    Started by wiredalchemist‎, 10-26-2015 08:49 PM
    • Replies: 1
    • Views: 579
    10-26-2015, 08:53 PM Go to last post
  35. Smile Need statistician

    Hi Gastrodoc from NY here. I work in a university hospital and have been working on epidemiological research. I am trying to find a statistician well...

    Started by gastrodoc‎, 10-25-2015 10:42 PM
    • Replies: 0
    • Views: 1,645
    10-25-2015, 10:42 PM Go to last post
  36. imultivariate analysis?

    Hi, I have some data looking at a few variables and whether they are different for patients receiving/not receiving certain treatment. They are a...

    Started by klara.m‎, 10-24-2015 08:13 AM
    • Replies: 3
    • Views: 1,476
    10-24-2015, 03:09 PM Go to last post
  37. Comparing data between >2 groups, not sure if continous

    hello everyone. I have a problem in deciding which test to solve this situation: I have 7 groups of patients, and I want to test wheter the...

    Started by TeoTeo‎, 10-23-2015 10:14 AM
    • Replies: 0
    • Views: 1,796
    10-23-2015, 10:14 AM Go to last post
  38. Cox regression with age as time scale and the proportional hazards assumption

    Hello. I am currently working on a Cox regression in SPSS (Complex Samples). The cox analysis has age as time scale and calendar year as...

    Started by rcordtz‎, 10-20-2015 02:56 PM
    assumption, cox proportional hazard, log-log plot, time scale
    • Replies: 0
    • Views: 4,085
    10-20-2015, 02:56 PM Go to last post
  39. Survival Analysis - how to deal with replicates

    Hi, I hope someone will be able to help me with my problem, which probably is plain simple. :confused: I work on immunity experiment with fruit...

    Started by Buckyball‎, 10-19-2015 08:42 AM
    • Replies: 5
    • Views: 3,099
    10-19-2015, 01:42 PM Go to last post
  40. Survival analysis

    I know this forum is probably not the right place to post my question, but considering the impressive help I have obtained hare and the (unimpressive...

    Started by Bio_Stat‎, 10-16-2015 01:48 PM
    • Replies: 3
    • Views: 1,475
    10-19-2015, 06:53 AM Go to last post
  41. Need help with Poisson Distribution

    Hi Everyone! I`ve been really stuck on a biostats question that just doesn`t seem to make sense. The work I have is Pr(X) = (e^-u) (u^x) / X!...

    Started by Opendome‎, 10-17-2015 04:40 PM
    • Replies: 4
    • Views: 1,873
    10-18-2015, 04:33 PM Go to last post
  42. sample size calculation non-inferiority trial

    Dear Sir I need your help with a sample size calculation. We are planning to do a phase 3 non-inferiority randomised study comparing chemotherapy...

    Started by venkat‎, 10-15-2015 01:56 AM
    • Replies: 4
    • Views: 3,210
    10-17-2015, 02:14 AM Go to last post
  43. 2 roc curves (from a study with 2 biomarkers) in one curve

    Hy, I have a problem about solving something in R. It's about 2 roc curves of a 2 biomarkers... and I have to plot it in one curve and calculate the...

    Started by raluca‎, 10-16-2015 08:59 AM
    roc curves
    • Replies: 3
    • Views: 2,521
    10-16-2015, 12:45 PM Go to last post
  44. Paired analysis/ Stuart-Maxwell test

    Hi everyone, I am performing a paired analysis, cases paired with controls, with each individual having a status of current,former or never. I...

    Started by yourela3‎, 10-15-2015 09:36 AM
    • Replies: 0
    • Views: 1,116
    10-15-2015, 09:36 AM Go to last post
  45. Determine Sample Size from Power for Two Sample Proportions

    Hello Everyone! I just changed to a more clinical-trials related biostatistics job and my boss, who has a clinical background, made a power...

    Started by daszlosek‎, 10-13-2015 07:28 AM
    • Replies: 0
    • Views: 1,211
    10-13-2015, 07:28 AM Go to last post
  46. RDA in Canoco; linear dependence between variables

    Hi, I would be most grateful for help regarding the question that I was asked by the journal editor. I have reviewed several papers and this forum...

    Started by Andrzej‎, 10-09-2015 02:02 AM
    • Replies: 2
    • Views: 2,755
    10-09-2015, 09:35 AM Go to last post
  47. accounting for left-truncation is STATA

    Hi, I have yet another question about survival analysis, this time regarding the appropriate code using STATA. I am trying to account for...

    Started by Basia.‎, 10-09-2015 08:49 AM
    • Replies: 0
    • Views: 1,587
    10-09-2015, 08:49 AM Go to last post
  48. survival analysis - concerns about duration times

    Hello, I'm very much a beginner at survival analysis - i know the basics, but I still get a bit lost when it comes to details. I am researching...

    Started by Basia.‎, 10-08-2015 06:03 AM
    duration, survival analysis
    • Replies: 1
    • Views: 1,097
    10-08-2015, 06:39 AM Go to last post
  49. Sample size calculation for Chi square Test

    Hi, I have trouble determining the sample size for a simple Chi Square Test. My problem is the following: I tried to calculate the sample size for...

    Started by ehi895‎, 08-30-2015 08:03 AM
    • Replies: 2
    • Views: 3,319
    10-02-2015, 08:36 AM Go to last post
  50. Autoregresive (AR) models and stationarity - Contradiction?

    Hello, I have a problem regarding the general understanding of autoregressive (AR) models (and related models, such as MA and AR(I)MA models)...

    Started by mmercker‎, 10-01-2015 01:15 PM
    ar model, arma, autoregressive, moving average process, time series
    • Replies: 0
    • Views: 1,152
    10-01-2015, 01:15 PM Go to last post
  51. Clinical research, Adequate statistical approach?

    Dear all! Having completed basic science projects, entering clinical research demands a whole set of other statistical approaches. Please help :-)...

    Started by DrDan‎, 09-28-2015 04:40 PM
    • Replies: 5
    • Views: 2,089
    09-28-2015, 09:38 PM Go to last post
  52. question about incidence and prevalence

    I have a question about incidence and prevalence, so maybe it's off topic (if so can anyone recommended another forum?) I have a paper that claims...

    Started by JuanT‎, 09-22-2015 12:07 AM
    incidence, prevalence
    • Replies: 4
    • Views: 1,668
    09-26-2015, 09:36 PM Go to last post
  53. homogeneity of risk ratio (relative risk) across strata

    Greetings all. In a stratified analysis, the Breslow-Day test evaluates homogeneity of odds ratios across strata. Is there a comparable test for...

    Started by js62‎, 09-25-2015 05:03 PM
    • Replies: 2
    • Views: 2,883
    09-25-2015, 08:59 PM Go to last post
  54. Change from or adjust for baseline for Binary outcomes

    Hi, any thoughts on how to estimate change from baseline, or adjust for baseline value when both the baseline value and the post-intervention...

    Started by DSB‎, 09-24-2015 02:54 AM
    binary data; baseline
    • Replies: 2
    • Views: 1,695
    09-24-2015, 07:24 AM Go to last post
  55. Sampling Behavior of a count

    Undercoverage is a problem that occurs in surveys when some groups in the population are underrepresented in the sampling frame used to select the...

    Started by robertshane‎, 09-21-2015 09:09 PM
    sampling, sampling distribution
    • Replies: 1
    • Views: 4,067
    09-21-2015, 09:22 PM Go to last post
  56. survival analysis - setting up data for Stata stset

    Hello, I've the following dataset: where: date0 and date1 are initial and final period phase=1 indicates expansion and phase=-1 contraction...

    Started by fralibero‎, 09-21-2015 08:47 AM
    • Replies: 0
    • Views: 1,959
    09-21-2015, 08:47 AM Go to last post
  57. Unhappy correlation between estimation of gestational age during pregnancy by diffl methods

    what statistical test should be used for finding correlation between gestational age estimated from clinical method and that from ultrasound during...

    Started by doel‎, 09-20-2015 02:26 AM
    • Replies: 6
    • Views: 3,034
    09-21-2015, 07:54 AM Go to last post
  58. a series of T tests more appropriate than ANOVA here?

    Hi all, I'm writing up some experimental results, which I believe I know how to analyze, but wanted to get some frank and impartial feedback before...

    Started by BWGIA‎, 07-03-2011 09:18 PM
    anova, dunnett t test, t test
    • Replies: 10
    • Views: 6,731
    09-19-2015, 05:02 AM Go to last post
  59. Applying Statistical Methods to Biophysical Chemistry Research, IDP Ensembles

    Hello! I am a second-year chemistry graduate student studying intrinsically disordered proteins (IDPs). IDPs do not adopt a stable folded state at...

    Started by katherynpenrod‎, 09-15-2015 12:39 AM
    biophysical, chemistry, help needed, methods, proteins
    • Replies: 0
    • Views: 1,393
    09-15-2015, 12:39 AM Go to last post
  60. How many B-type colonies should I test?

    Here is a current problem from my research project I could use some help with. Of four colonies from genetic background A, two have phenotype X. ...

    Started by rcorrea21‎, 09-14-2015 07:45 PM
    • Replies: 0
    • Views: 1,233
    09-14-2015, 07:45 PM Go to last post

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