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Forum: Biostatistics

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

  1. How to interpret the results?

    Hello Sir or Madam,and all guys, Tomoorow i have to handin my answers on exam , and unfortunately ,i have this question , i can not answer , i will...

    Started by maysa‎, 09-29-2005 01:27 AM
    • Replies: 2
    • Views: 7,168
    09-29-2005, 12:10 PM Go to last post
  2. best biostatistics textbook?

    I have Health and Numbers. I'd like to get another book to supplement. Recommendations? Looking for clear and simple! Thanks!

    Started by kalbright36‎, 09-29-2005 09:58 PM
    • Replies: 3
    • Views: 12,695
    10-05-2005, 11:26 PM Go to last post
  3. Iam stuck with this tough question

    Dear admistrator, Thanks for help me with this hursh course , please my assignment will be after less than 18 hours, so Iam looking forward toe...

    Started by mousa‎, 10-17-2005 02:40 PM
    • Replies: 1
    • Views: 3,229
    10-17-2005, 02:53 PM Go to last post
  4. Help

    Ok Guys not sure if I'm looking at these questions rite... can someone give me there opion of the correct answers? Thanks! The t test for...

    Started by chadxc1‎, 11-14-2005 06:45 PM
    • Replies: 1
    • Views: 7,384
    11-14-2005, 08:04 PM Go to last post
  5. Odds ratios

    Hi John: I just want to understand the term ORs. In logistic regression, we have ORs as effect size, correct? And also, we can calculate ORs based...

    Started by Susanbwh‎, 02-21-2006 12:32 PM
    • Replies: 1
    • Views: 4,941
    02-21-2006, 12:41 PM Go to last post
  6. Matched analysis for ordinal data

    Hi folks, I have data from a matched case-control study (4 controls per case). Matching is on age and gender. Using Epi-Info and SPSS I am...

    Started by Peter Horby‎, 02-22-2006 09:55 PM
    • Replies: 2
    • Views: 4,459
    02-22-2006, 11:32 PM Go to last post
  7. Sensitivity and z scores

    Can I compare the sesitivities of two tests using the Z test? THanks

    Started by lostinspace‎, 08-09-2006 04:46 PM
    • Replies: 1
    • Views: 3,370
    08-10-2006, 11:27 PM Go to last post
  8. Calculating significance for indepent samples

    Hello to you all. I would be very happy if anyone would mind helping me with a little problem I have encountered whilst doing some research. I am...

    Started by Orthoteer‎, 09-16-2006 02:31 AM
    • Replies: 2
    • Views: 3,070
    09-17-2006, 10:29 PM Go to last post
  9. time dependent covariate transplant analysis

    I need to analyse data where i need to look at survival of patients on transplant waiting list , some of whom have received transplants. I need to...

    Started by kallady43‎, 11-09-2006 06:07 AM
    • Replies: 0
    • Views: 2,737
    11-09-2006, 06:07 AM Go to last post
  10. How to test for differences between sevaral factors

    Hi there, quite new to stats and was wondering whether someone can help with this? I've just finished an experiment investigating the survival...

    Started by Tt3‎, 11-15-2006 08:00 PM
    • Replies: 0
    • Views: 2,287
    11-15-2006, 08:00 PM Go to last post
  11. Looking for some assistance

    The project is on testing for measles and how your antibody levels have to be greater than the cut off value in order for you to test positive. ...

    Started by monthecelts‎, 11-23-2006 12:42 PM
    • Replies: 0
    • Views: 2,985
    11-23-2006, 12:42 PM Go to last post
  12. Logistic regression

    I'm studying for my comprehensive exams. I have read several texts on logistic regression and have found discrepancies between the definition and...

    Started by teanabeana‎, 12-20-2006 05:21 PM
    • Replies: 0
    • Views: 3,045
    12-20-2006, 05:21 PM Go to last post
  13. Unhappy Flora Z Statistic

    Hi, I am a Post-Graduate Surgical Resident working on my Thesis. I need to analyze my data using the 'Flora Z Statistic'. Unfortunately even the...

    Started by jipmerite‎, 01-05-2007 12:51 PM
    • Replies: 2
    • Views: 4,525
    01-07-2007, 12:14 PM Go to last post
  14. Causal inferences in surveys??

    Hi, I am looking into the general problems of making causal inferences in surveys. There are a few points I am still confused: a)In what ways...

    Started by aquary‎, 01-08-2007 06:17 PM
    • Replies: 1
    • Views: 3,122
    01-10-2007, 05:27 PM Go to last post
  15. Statistics Question

    Andre is fearless circus performer who gets shot from a special cannon during the grand finale of the show and is supposed to land on a safety net at...

    Started by alexkeytone‎, 04-14-2007 05:40 PM
    • Replies: 0
    • Views: 3,505
    04-14-2007, 05:40 PM Go to last post
  16. Kaplan-Meier Survival Analysis - Why P-value of 0.10?

    Hi all..I've been searching for ages and I just can't work out why the kaplan0meier survival analysis in SPSS suggested using P-value of 0.10 as a...

    Started by shan‎, 05-28-2007 12:04 AM
    • Replies: 0
    • Views: 7,122
    05-28-2007, 12:04 AM Go to last post
  17. undefined odds ration

    Hi everybody, i have a problem in calculation of odds ratio if one cells was zero. has any one any idea about how to calculate it? thank you for...

    Started by Ghada‎, 06-23-2007 02:35 PM
    • Replies: 6
    • Views: 7,940
    06-28-2007, 03:10 PM Go to last post
  18. Backward logistic regression

    :wave: Hi ...This is my first posting. After reviewing the talkstats archives for info on regression analyses, I turn to talkstats subscribers for...

    Started by dataquest‎, 07-05-2007 05:48 AM
    • Replies: 4
    • Views: 7,772
    07-10-2007, 03:52 AM Go to last post
  19. Smile question about determining clinical significance cutof

    Hi, I have a parenting measure that I would like to construct a multinomial outcome from (4 categories). I am constructing it as follows from two...

    Started by sten‎, 08-16-2007 09:36 PM
    • Replies: 1
    • Views: 3,217
    08-16-2007, 10:21 PM Go to last post
  20. Question Reproducibility

    I was reading "Sample Size Calculations in Clinical Research", a book by Chow, Shao, and Wang. On p. 6 there is a table of the probability that a...

    Started by Michael Schmidt‎, 08-20-2007 10:42 AM
    • Replies: 0
    • Views: 3,111
    08-20-2007, 10:42 AM Go to last post
  21. Exclamation Another Confidence Interval Qn!

    How do I do this? It is claimed that a new treatment for prolonging the lives of cancer patients is more effective than the standard one. The...

    Started by georgina_009‎, 10-02-2007 10:18 PM
    • Replies: 0
    • Views: 2,566
    10-02-2007, 10:18 PM Go to last post
  22. Biostatistics

    Hi guys, Newbie here. From Malaysia. I am a medical doctor trying biostatistics. Anybody else with similar background? :D

    Started by DrJ‎, 10-08-2007 10:14 PM
    • Replies: 0
    • Views: 2,821
    10-08-2007, 10:14 PM Go to last post
  23. Question Probit Analysis on Limited Data

    My problem is how to address data on mortality rates of spiders exposed to three temperatures. I have done probit to analyse similar data with...

    Started by kencil‎, 07-20-2007 10:29 AM
    • Replies: 4
    • Views: 3,998
    10-23-2007, 07:11 AM Go to last post
  24. who can provide good forum about clinical trial data management and biostatistics?

    thank you very much!!!多谢大家啦!!!

    Started by orientaldream‎, 10-29-2007 11:08 PM
    • Replies: 0
    • Views: 5,800
    10-29-2007, 11:08 PM Go to last post
  25. LD50 power analysis

    Hello all, I come from a biology background, and I wanted to ask a question. We have a value of LD50 (lethal dose), which is the dose at which 50%...

    Started by Shiranai‎, 11-08-2007 05:56 PM
    • Replies: 2
    • Views: 4,500
    11-09-2007, 02:22 PM Go to last post
  26. Question I need so much help in statistics....I have alot of questions, please help me.

    Hi there, Im taking a statistics class online right now because Im going for a degree in Bio technology. When I comes to math I just get so confused...

    Started by megank‎, 11-11-2007 01:14 PM
    • Replies: 1
    • Views: 8,258
    11-12-2007, 11:18 AM Go to last post
  27. Writing a Life Regression Model with Minitab Output

    Alrighty, I feel incredibly dumb here so please bear with me. :( I have the following output from minitab from a life regression. Now, what I want...

    Started by IronMan‎, 11-08-2007 05:20 PM
    • Replies: 1
    • Views: 3,859
    11-15-2007, 10:48 AM Go to last post
  28. EBM Stats

    Hi everyone - my first post! Was wondering if anyone could help me. I am doing a project on the outcomes of a particular type of eye surgery...

    Started by 7up‎, 11-13-2007 07:30 AM
    • Replies: 1
    • Views: 2,711
    11-25-2007, 12:23 PM Go to last post
  29. Angry Null Hypothesis for OR

    I got this question: "In the background for this study, the authors mentioned that “Data from the Sleep Heart Health Study (Baldwin et al., 2001)...

    Started by abrenner‎, 11-28-2007 02:55 PM
    • Replies: 1
    • Views: 3,677
    11-28-2007, 07:23 PM Go to last post
  30. hello all, please help me choose the statistical test for my research

    I am looking at a database and would need help on what statistical test to use for my research project. There are four groups (for example cars...

    Started by mdme‎, 01-03-2008 12:07 PM
    • Replies: 2
    • Views: 4,102
    01-12-2008, 05:57 AM Go to last post
  31. Relative Impact of Predictors with a Binary Logistic Regress

    Hi, I'm trying to find a means to interpret the odds ratios resulting from a binary logistic regression. I have a binary response variable and...

    Started by Crystal‎, 02-19-2008 07:59 PM
    • Replies: 0
    • Views: 2,515
    02-19-2008, 07:59 PM Go to last post
  32. Odds ratios and regression

    It's my understanding that odds ratios derived from (multiple) logistic regression is based upon a single unit increase of your variables. If the...

    Started by BenW‎, 02-28-2008 07:48 AM
    • Replies: 0
    • Views: 2,808
    02-28-2008, 07:48 AM Go to last post
  33. logistic regression

    in logistic regression what does an exp 1 means? that the odds increase or that they remain the same?

    Started by casiva‎, 03-12-2008 10:55 AM
    • Replies: 1
    • Views: 3,874
    03-12-2008, 12:14 PM Go to last post
  34. Which test to use for correlation between groups using ordinal values?

    I am trying to test a hypothesis that different decision traps are caused by the same common cause. In the complete picture there are abt 30 decision...

    Started by rlammers‎, 04-01-2008 07:41 AM
    • Replies: 0
    • Views: 3,605
    04-01-2008, 07:41 AM Go to last post
  35. Odds ratio

    I am studying risk for cardiovascular disease depending on two different biomarkers. The study -design is a case-control study and I have...

    Started by JonasPerssonSthlm‎, 04-14-2008 05:05 AM
    • Replies: 0
    • Views: 3,295
    04-14-2008, 05:05 AM Go to last post
  36. Question I Need help with median and variance...

    ::wave: hi every1 .. i need help with a biostatistics problem... well it was in spanish so i dont know if i made a good job translating but they are...

    Started by Js1&OnLY‎, 04-22-2008 06:17 PM
    • Replies: 1
    • Views: 2,495
    04-22-2008, 06:23 PM Go to last post
  37. unsure about response

    For the data set below, I want to fit a model for log seizure rate, including the main effect of treat and time (as categorical variable with 5...

    Started by dwen‎, 05-30-2008 09:30 PM
    • Replies: 1
    • Views: 3,344
    06-01-2008, 05:04 AM Go to last post
  38. Not sure which test to use...

    Hi everyone, thanks for reading. I'll try and make this quick, so that hopefully once I know which test I should use I can go and have a go rather...

    Started by Stuck‎, 06-08-2008 08:27 AM
    • Replies: 0
    • Views: 2,288
    06-08-2008, 08:27 AM Go to last post
  39. stats for following nominal variables over time??

    Hi all, I'm trying to find a method of examining the patterns in symptoms over time. These are only nominal categories. Each patient has...

    Started by hmwestern‎, 07-17-2008 03:39 PM
    • Replies: 1
    • Views: 2,752
    07-17-2008, 03:54 PM Go to last post
  40. likelihood ratio for censored data

    hi, I'm working on multiply censored data. In order to check which is the law my data follow(weib vs exp), i need to do a test. For the moment,...

    Started by edwin_35‎, 07-25-2008 04:08 PM
    • Replies: 1
    • Views: 4,008
    07-27-2008, 09:35 AM Go to last post
  41. Repeated measures with censoring

    I am conducting an experiment to test spin times of tops. I have 5 aluminum tops and 5 wooden tops. I spin each top 3 times with a maximum spin...

    Started by wayne‎, 08-04-2008 07:41 PM
    • Replies: 2
    • Views: 2,769
    08-05-2008, 12:23 PM Go to last post
  42. Clinical Study and Biostatistics

    Hy everyone, I have measured a biological parameter in a cohort of 20 patients before they start a therapy (baseline) and then every 2 months for a...

    Started by mnasi‎, 08-21-2008 08:42 AM
    • Replies: 2
    • Views: 2,835
    08-26-2008, 05:19 AM Go to last post
  43. diagnostic testing

    Medical Testing When evaluating a diagnostic test, one typical constructs a 2 x 2 table and calculates the specificity and sensitivity (true and...

    Started by denmanbw‎, 01-22-2008 01:01 PM
    • Replies: 1
    • Views: 3,050
    08-30-2008, 05:45 AM Go to last post
  44. Question Calculating sensitivity and specificity of a *battery* of tests

    Hello everyone! I need to calculate the specificity, sensitivity, positive and negative predictive values of a battery of neuropsycholocial...

    Started by bergier‎, 07-09-2008 03:49 PM
    • Replies: 3
    • Views: 6,819
    08-30-2008, 05:52 AM Go to last post
  45. Wink biostatistical problem--birds and patch size

    I have an interesting statistical problem I'm having trouble solving...here's the story: I repeatedly sampled birds along 100m-long transects in...

    Started by birdman‎, 09-15-2008 11:57 AM
    • Replies: 5
    • Views: 3,383
    09-17-2008, 07:40 AM Go to last post
  46. More Repeated Measures Problems!

    Hi guys, I have a similar question to johnstephenbyrne. I am analysing the results of a clinical trial. I have measured the levels of a cytokine...

    Started by timric‎, 09-08-2008 07:08 PM
    • Replies: 2
    • Views: 4,030
    09-17-2008, 04:22 PM Go to last post
  47. Plotting PPV vs. NPV, why?

    Hi, I was asked to plot PPV vs NPV, and I'm not sure what such a plot does in general. Is it similar to an ROC curve (sensitivity vs....

    Started by pufftissue‎, 10-01-2008 12:51 PM
    • Replies: 0
    • Views: 4,558
    10-01-2008, 12:51 PM Go to last post
  48. Logistic regression with continuous variables

    I have levels of eight biochemical markers (continuous variables) and want to determine whether each marker helps to predict the presence or absence...

    Started by rbody‎, 10-06-2008 03:54 PM
    • Replies: 4
    • Views: 11,560
    10-07-2008, 05:26 AM Go to last post
  49. Help! Data layout and which test?

    Hi, :wave: I have some data on a clinical trial. 2 Independent groups, running in paralell, treatment and placebo(n=50). Biological markers...

    Started by stinker‎, 09-30-2008 10:03 AM
    • Replies: 3
    • Views: 3,438
    10-14-2008, 08:06 AM Go to last post
  50. What do YOU mean by "statistically significant"?

    Here's a question more about communication than statistical methods. I've experienced that the term "statistically significant" is used often by...

    Started by jawon‎, 10-06-2008 06:19 PM
    2 Pages
    1 2
    • Replies: 25
    • Views: 13,516
    10-22-2008, 04:40 PM Go to last post
  51. omnibus test

    Hi Is it possible to explain me what's an Omnibus Test ??? I find some definitions on Internet but there is'nt some good concrete example ... ...

    Started by viwel‎, 10-28-2008 09:19 AM
    • Replies: 4
    • Views: 29,798
    10-30-2008, 09:00 AM Go to last post
  52. One for the pros: conditional logistic regression discrepancy

    Ok here´s the problem. I am using R version 2.8.0 on a Windows XP machine. I am not a statistician. I am trying to perform a conditional...

    Started by pisti‎, 11-04-2008 12:14 PM
    • Replies: 8
    • Views: 8,272
    11-07-2008, 06:49 AM Go to last post
  53. Help decide whether I used the right tests

    Hi, I have been doing some statistical tests which I'm a little bit out of my depth on for work. The person I'm doing them for knows less than me,...

    Started by somnum‎, 11-18-2008 10:48 PM
    • Replies: 2
    • Views: 3,183
    11-19-2008, 05:14 PM Go to last post
  54. Is it ok to average ranks?

    Dear users, I have a following problem, I have a matrix of results of testing of some chemical substances on a set of various experimental objects....

    Started by gemko‎, 11-26-2008 03:55 PM
    • Replies: 0
    • Views: 2,923
    11-26-2008, 03:55 PM Go to last post
  55. Equal Odds

    I'm trying to figure out how I can use logistic regression to test the hypothesis of equal odds in a 2 x 2 table of counts? Any ideas? I know I have...

    Started by jessicka24‎, 12-07-2008 05:47 PM
    • Replies: 1
    • Views: 2,991
    12-07-2008, 10:20 PM Go to last post
  56. Random Effects Regression vs. Fixed Effects Regression

    I'm having trouble distinguishing when to use random effects versus fixed effects regression. Any thoughts?

    Started by Veronica‎, 12-09-2008 07:44 PM
    • Replies: 6
    • Views: 35,295
    12-10-2008, 08:19 AM Go to last post
  57. HIV-Testing in the desert

    Hi, In a lot of popular books about statistics (at least in Germany) there is this example about HIV. Even with a sensitivity of say 99%, the...

    Started by giordano‎, 12-14-2008 11:04 AM
    • Replies: 1
    • Views: 3,040
    12-15-2008, 12:40 PM Go to last post
  58. Help me

    Dear Sir, My wife is a Post Graduate student of Ophthalmology. We desperately seek your help in the analysis of her desertation work. The objectives...

    Started by drriteshsingh‎, 12-14-2008 11:15 AM
    • Replies: 1
    • Views: 2,160
    12-15-2008, 10:21 PM Go to last post
  59. clinical statistics book

    Hi, I'm lokking for a book about clinical statistics like this one : 4thEdition Clinical Epidemiology / The essentials / Fletcher & Fletcher ...

    Started by viwel‎, 12-10-2008 09:01 AM
    • Replies: 1
    • Views: 3,510
    12-18-2008, 08:56 AM Go to last post
  60. Incorporating time series date into before/after intelligence testing? (n00b alert)

    Hello there! A short introduction: My background is pure maths and computer science however I did not take anything past first year statistics at...

    Started by boing‎, 12-28-2008 04:21 AM
    • Replies: 1
    • Views: 2,405
    12-28-2008, 05:14 PM Go to last post

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