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Forum: Biostatistics

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

  1. Vitamin D deficiency & disease outcomes - assistance with interpretation of SPSS res

    Hello everybody! As part of my diploma work on the effects of vitamin D deficiency I'm incorporating results from a cross-sectional survey on a...

    Started by gaggantas33‎, 01-20-2015 10:06 AM
    • Replies: 2
    • Views: 114
    Yesterday, 04:04 AM Go to last post
  2. getting in deep..

    Hello, I am attempting to do statistical analysis on data that I've collected, but I am starting to feel overwhelmed by the choices as I read...

    Started by rocketmotor‎, 01-29-2015 11:11 PM
    • Replies: 1
    • Views: 57
    Yesterday, 03:53 AM Go to last post
  3. P-values with confidence intervals - where do they come from?

    Below is quoted a part of my comments in reviewing a scientific paper. I'm not a statistician so I want to make sure I'm not missing something. Do...

    Started by Johann Kotze‎, 01-29-2015 03:14 PM
    • Replies: 2
    • Views: 82
    Yesterday, 03:46 AM Go to last post
  4. regression with covariates having "structural" zeros in contingency table

    Hello. I'm examining associations of various risk behaviors within a clinical cohort on having a suppressed or un-suppressed HIV viral load using...

    Started by psacamano‎, 01-29-2015 05:58 PM
    • Replies: 0
    • Views: 49
    01-29-2015, 05:58 PM Go to last post
  5. help calculating needed sample size

    hi im conducting a study on a certain ratio in a blood exam (lets call it X) . I aim to say that there is a certain sensitivity (let say>80%) for...

    Started by urilee‎, 01-25-2015 04:18 AM
    • Replies: 1
    • Views: 182
    01-28-2015, 05:43 PM Go to last post
  6. Multiple Imputation in R on variable with repeated measurements

    Hello! I am working with an occupation cohort exposed to radiation and have a dataset containing a number of variables on each worker, including...

    Started by PamD‎, 01-22-2015 03:12 PM
    • Replies: 0
    • Views: 148
    01-22-2015, 03:12 PM Go to last post
  7. Median follow Up shorter than median over all survival, possible?

    Hello, I calculated overall survival and median follow up with Kaplan Meyer. In particular follow up was calculated as inverse of overall...

    Started by greeklatin‎, 01-22-2015 09:04 AM
    • Replies: 2
    • Views: 84
    01-22-2015, 11:15 AM Go to last post
  8. Project Issue.

    I am a student of statistics discipline. I have to conduct a project which i can apply in society or nation. My preferable topics are...

    Started by Cynderella‎, 01-22-2015 04:55 AM
    applied statistics, biostatistics, project, research for thesis, self-study
    • Replies: 0
    • Views: 105
    01-22-2015, 04:55 AM Go to last post
  9. Which test to use?

    Hello guys, I am conducting a study to evaluate the effect of supplementation on serum vitamin levels. There are four categories based on the...

    Started by bsing82‎, 01-20-2015 01:48 AM
    • Replies: 5
    • Views: 226
    01-21-2015, 04:49 AM Go to last post
  10. Determining seasonal sample size

    I intend to deploy a new sonar system at our weir to help us count migrating fish. This new system cannot identify gender. We have six years of...

    Started by KellyD‎, 01-20-2015 04:07 PM
    • Replies: 0
    • Views: 111
    01-20-2015, 04:07 PM Go to last post
  11. Really new at this - need help

    Hello friend, I al 18 years old and taking a bio stat class. I have never taken stats and I;m really poor in math. Could someone help break...

    Started by Pammy‎, 01-20-2015 07:18 AM
    • Replies: 3
    • Views: 108
    01-20-2015, 02:27 PM Go to last post
  12. Help finding appropriate test when observations are non-independent

    I have a data set consisting of data from 7 islands. I have measured the average gene flow between each pair of islands as well as the difference in...

    Started by mlogan1983‎, 01-20-2015 12:23 PM
    biostatistics, correlation, independence, non parametric, pairwise comparisons
    • Replies: 0
    • Views: 67
    01-20-2015, 12:23 PM Go to last post
  13. Struggling with this power/effect size analysis, any help?

    Hello all, I am trying to calculate the effect size or power analysis for this study to assess my probability to detect a phenomenon/change, here are...

    Started by Ralph84‎, 01-20-2015 06:40 AM
    • Replies: 0
    • Views: 69
    01-20-2015, 06:40 AM Go to last post
  14. Question Ecology: how to compare "intrinsic growth rates" (r)

    Hi everybody, I would like to know how to statistically compare different "intrinsic growth rates", most of the times named "r", belonging to...

    Started by Reset85‎, 01-19-2015 11:13 AM
    ecology, ecotoxicology, euler-lotka, intrinsic growth rate, toxicology
    • Replies: 0
    • Views: 99
    01-19-2015, 11:13 AM Go to last post
  15. Locating significantly different data points in a sample

    Hi, I have question regarding some data I collected recently which can be represented as plain integers (basically the number of features (dots)...

    Started by mxs‎, 01-18-2015 02:32 PM
    • Replies: 3
    • Views: 177
    01-19-2015, 06:32 AM Go to last post
  16. [Study design] is this a version of crossover design

    Hello, I came across a set of data comparing 2 medical approaches in terms of several continuous variables (Primary objective is compare A to B). ...

    Started by drmb‎, 01-16-2015 08:37 AM
    • Replies: 0
    • Views: 130
    01-16-2015, 08:37 AM Go to last post
  17. [Clustered Robust Standard Error] - Custering

    I am investigating the effects of age and exercise in protein expression in mouse motor neurons. I have four groups each with a limited number of...

    Started by brajo083‎, 01-15-2015 06:06 PM
    cluster analysis, logistic regression, regression, robust
    • Replies: 1
    • Views: 144
    01-15-2015, 08:41 PM Go to last post
  18. Thankfor for help in evaluating survival prognosis

    Hi! I'am investigating into the survival between two cohorts of incident patients. One historical (1986-1996) and one contemporary (2002-2012). I...

    Started by polarkakan2‎, 01-14-2015 04:51 PM
    • Replies: 1
    • Views: 126
    01-14-2015, 06:56 PM Go to last post
  19. Post Need help for selecting method

    I have a 4-group of data.in each group,there are 2 subcolumns which are before and after treatment.to analyse this which statistical method should I...

    Started by Yusupjan‎, 01-13-2015 05:01 PM
    • Replies: 1
    • Views: 183
    01-14-2015, 03:14 PM Go to last post
  20. Disproportional Sampling for Uneven Case Controls

    Hello, I am looking to do a random sampling analysis of a case/control dataset containing 6X as many controls as cases. Therefore, I need to...

    Started by rdoan‎, 01-13-2015 09:33 AM
    case control, disproportional sampling, random sampling, sampling
    • Replies: 0
    • Views: 112
    01-13-2015, 09:33 AM Go to last post
  21. Help on bachelor's thesis!

    Hey everyone! I'm trying to analyse my bachelor's thesis data in SPSS, but I'm not entirely confident I'm using the right methods. Could you...

    Started by Scoltey‎, 01-12-2015 05:04 AM
    • Replies: 0
    • Views: 300
    01-12-2015, 05:04 AM Go to last post
  22. Type 1 or type 3 analysis?

    I'm trying to fit various models (I had been doing negative binomial, but then had to switch to Poisson in some cases because of the model being...

    Started by wernie07‎, 01-11-2015 01:11 PM
    • Replies: 0
    • Views: 223
    01-11-2015, 01:11 PM Go to last post
  23. Case control study - selection of control group

    I am starting a nested case control study using a pre existing dataset. I want to look at patient factors associated with relapse of tuberculosis. I...

    Started by andros23‎, 01-07-2015 11:12 AM
    case control; matched, stata commands
    • Replies: 4
    • Views: 216
    01-09-2015, 04:58 PM Go to last post
  24. Use of tnm as continuous variable in univariate or multivariate analysis

    Hello, I hope I put this post in the correct group. May I use TNM stage (1,2,3....), N stage (0,1,2,3.....) or grade (1,2,3,4....) as...

    Started by greeklatin‎, 01-08-2015 02:00 PM
    • Replies: 2
    • Views: 180
    01-09-2015, 03:56 AM Go to last post
  25. Multiple imputation

    I am doing a research about Aids in my city in Yemen. Unfortunately I have many missing data . So I used SPSS multiple imputation. I am not sure...

    Started by Alyamani‎, 01-07-2015 07:29 AM
    • Replies: 2
    • Views: 166
    01-08-2015, 01:22 AM Go to last post
  26. Using survival analysis to predict scope of truncated data

    I'm not sure I'm thinking about this correctly, and would be grateful for any insight as I think the problem is analogous to one that comes up in...

    Started by rboucherdata‎, 01-07-2015 05:30 PM
    event history analysis, forecasting, survival analysis, truncation
    • Replies: 0
    • Views: 117
    01-07-2015, 05:30 PM Go to last post
  27. Help with kaplan meier analysis in SPSS

    HI! Thank you very much in advance for helping with my post! I am a phd student, I do surgical research at the carotid artery. My current...

    Started by phdSPPShelp‎, 01-04-2015 09:59 AM
    biostatistics, spss, survival analysis
    • Replies: 2
    • Views: 271
    01-07-2015, 05:13 PM Go to last post
  28. Question about population matching procedure

    Good evening everyone, I am currently conducting a clinical trial where I am taking an intervention population (which is referred to a new...

    Started by cardgage‎, 01-06-2015 10:42 PM
    matching, matching data
    • Replies: 1
    • Views: 158
    01-07-2015, 02:56 AM Go to last post
  29. limts and probability

    I am looking at code and I do not understand it. The values T and R are natural logs and the expression given is (T-R)^2 -(std error)^2. I do ...

    Started by Angus McLean‎, 01-06-2015 06:28 PM
    • Replies: 1
    • Views: 126
    01-06-2015, 09:48 PM Go to last post
  30. Prediction versus Association: what's the difference?

    Hi! I wonder how to evaluate the performance of the tools that associate a variable (example: SNP, gene...) with a phenotype. In a few papers ,...

    Started by scratchscratch‎, 12-29-2014 06:17 AM
    • Replies: 0
    • Views: 263
    12-29-2014, 06:17 AM Go to last post
  31. little help, incidence rate with lost to follow-up

    hi there, i hope you can help me. I am studying for a test and there is an answer that i cannot solve... it asks to calculate the annual incidence...

    Started by onosonussen1‎, 12-24-2014 07:25 AM
    incidence rate, lost to follow-up
    • Replies: 1
    • Views: 290
    12-24-2014, 09:44 AM Go to last post
  32. ANOSIM: significant p-value and small R-value. How?

    I am analyzing data of a large sample size ('000's of samples) via one-way ANOSIM. Results appear contradictory: Highly significant p-value...

    Started by dt87‎, 12-21-2014 11:22 PM
    • Replies: 5
    • Views: 390
    12-22-2014, 10:21 PM Go to last post
  33. Repeated measures or two-way ANOVA ? + sample size estimation

    A sample of patients will undergo two treatments. Each patient will receive both treatments.One treatment will on the left side and the other...

    Started by Logician‎, 12-21-2014 07:40 AM
    • Replies: 3
    • Views: 268
    12-21-2014, 04:40 PM Go to last post
  34. case control study

    i want to do a study i have with me serum cholesterol levels of patients with intracerebral hemorhage and infarcts other studies some say low...

    Started by valsa‎, 12-21-2014 02:07 AM
    • Replies: 1
    • Views: 210
    12-21-2014, 09:03 AM Go to last post
  35. Unhappy A dumb question about univariate analysis (repost from applied statistics)

    Hello I'm quite dumb regarding statistics, but i really am looking for a simple answer to a simple question. the question is: how do i explore data...

    Started by Kimboz‎, 12-19-2014 04:05 AM
    • Replies: 2
    • Views: 295
    12-19-2014, 05:54 AM Go to last post
  36. Two-proportion z test: is it best for my problem, and can I pool data?

    I am examining populations (cultures) of yeast cells and scoring them for a particular trait. The data is categorical; within a population, a yeast...

    Started by dmcameron‎, 12-18-2014 04:24 PM
    pooling data, proportion test, z-test
    • Replies: 0
    • Views: 226
    12-18-2014, 04:24 PM Go to last post
  37. Repeated-measure ANCOVA

    Hi there, I'm looking at a study which is measuring the effect of medication A on aggressive behaviour over time, after they have failed...

    Started by cheoksoon‎, 12-16-2014 05:20 AM
    • Replies: 0
    • Views: 186
    12-16-2014, 05:20 AM Go to last post
  38. Any statisticians out here please? 50 voucher offer

    I am doing a survey as part of my MSc project and need someone to review the protocol from a stats point of view, including helping to determine the...

    Started by brownbabygirl‎, 08-11-2014 04:13 PM
    2 Pages
    1 2
    • Replies: 23
    • Views: 2,202
    12-15-2014, 06:28 PM Go to last post
  39. Salmon gender

    During the salmon run we have a daily count of fish, males and females. I want to determine if there is an equal probability each day of getting an...

    Started by KellyD‎, 12-11-2014 06:16 PM
    • Replies: 6
    • Views: 346
    12-13-2014, 05:46 AM Go to last post
  40. clinical trial interpretation

    Hi! given two randomised clinical trials, the first compare treatment A vs B; the second compare treatment A vs B vs C. after enrolment, the...

    Started by stator‎, 12-12-2014 02:32 PM
    clinical trial
    • Replies: 5
    • Views: 226
    12-12-2014, 07:57 PM Go to last post
  41. Preparing for Meta Analysis

    Hello Everybody, I am a physician and a researcher, have been studying the meta-analysis subject for a while now, and we are in the process to...

    Started by messadua‎, 11-15-2014 07:30 AM
    database, diagnostic test, meta analysis, predictors, structure
    • Replies: 1
    • Views: 313
    12-12-2014, 05:12 PM Go to last post
  42. Compare 2 tests - Bland Altman vs. area under curve

    Hello, I want to compare the performance of 2 binary classification tests (positive vs. negative diagnosis) from the same sample (n=430). I have...

    Started by finnakerstrom‎, 12-09-2014 04:15 PM
    bland-altman, roc curves
    • Replies: 6
    • Views: 310
    12-10-2014, 01:54 AM Go to last post
  43. Smile Where Do I Start?

    I need assistance with the following problem: In 1960, census results indicated that the age at which American men first married had a mean of...

    Started by sditizio‎, 12-09-2014 12:12 AM
    • Replies: 3
    • Views: 286
    12-09-2014, 08:00 AM Go to last post
  44. Normality assumption for ARIMA analysis

    I have two time series that I wish to quantify their relationship using arima analysis. Both data series are not normally distributed, even after...

    Started by SandraC‎, 12-07-2014 06:13 AM
    • Replies: 0
    • Views: 203
    12-07-2014, 06:13 AM Go to last post
  45. Help needed, linear regression SPSS for birthweight controlling for maternal age

    Hello all, I am in need of help. I am performing a study looking at the effects of Assisted Reproductive Technology on birthweight, and I would...

    Started by ironslave‎, 12-05-2014 11:07 AM
    • Replies: 0
    • Views: 199
    12-05-2014, 11:07 AM Go to last post
  46. Power Calculation

    I will admit that I have not sat around racking my brain on this one, but thought it may be nice to get some input. I was enlisted to help out...

    Started by hlsmith‎, 03-11-2014 11:46 AM
    • Replies: 4
    • Views: 507
    12-05-2014, 04:17 AM Go to last post
  47. Follow-up tests with 2-way within-subject repeated measures ANOVA

    Hi everybody, I've been doing a 2-way within-subject repeated measures ANOVA and I have some questions: 1) Is it correct that I'm only...

    Started by Eric2014‎, 12-04-2014 12:19 PM
    anova, follow-up, t-test
    • Replies: 0
    • Views: 302
    12-04-2014, 12:19 PM Go to last post
  48. data exploration continue dependent variable or categorical dependent variable ?

    Hello everyone if you are give a data set with age ask outcome(dependent variable) but in the data set age has two scale categorical and...

    Started by dockiss‎, 12-04-2014 05:32 AM
    • Replies: 0
    • Views: 167
    12-04-2014, 05:32 AM Go to last post
  49. How can I obtain contrast statment for linear trend test ?

    Hi, I hope someone can explain this to me. I have obtained the following from the SAS website, but I cannot apply it to my data where I have 11 dose...

    Started by Bracknell‎, 11-27-2014 06:18 AM
    • Replies: 3
    • Views: 382
    12-02-2014, 09:18 AM Go to last post
  50. Should I use a two sample or paired t.test?

    Hello, Ive just wanted to post one simple question. I am comparing the removed area through endonasal approach in left or right side. It means,...

    Started by emilio.gonzalez.martinez‎, 11-23-2014 05:44 PM
    comparing, paired test
    • Replies: 5
    • Views: 510
    11-28-2014, 07:40 AM Go to last post
  51. Cox-analysis: right approach in this case?

    Hello all, I would be interested in your thoughts about whether this approach sounds correct to you or not. I have data of a cohort of subjects...

    Started by Ralph84‎, 11-28-2014 06:19 AM
    • Replies: 0
    • Views: 173
    11-28-2014, 06:19 AM Go to last post
  52. Paired t test or two sample ANOVA

    Hi, The experiment is investigating whether IQ changes based on certain training (there are 2 courses and a control - nothing). I have the IQ of...

    Started by roosterrocky‎, 11-26-2014 07:19 PM
    • Replies: 2
    • Views: 299
    11-27-2014, 01:03 PM Go to last post
  53. Which tests and steps to do?

    Hey there! I am new to this so I would really really appreciate any help! I haven't got statistical education but still I have to use it, so I want...

    Started by Veronikite‎, 11-27-2014 04:49 AM
    • Replies: 0
    • Views: 176
    11-27-2014, 04:49 AM Go to last post
  54. Where can I access the actual DATA used from medical studies?

    Hello, I have a project in my regression class where I need to find 2 studies that used regression analysis, and I need to reproduce their...

    Started by BearJewJ‎, 11-16-2014 12:59 PM
    • Replies: 3
    • Views: 409
    11-18-2014, 10:53 AM Go to last post
  55. Test to look at increasing admission incidence in a population

    We are trying to establish if a significantly higher proportion of obstetric patients in our hospital are being admitted to intensive care than...

    Started by RikThomas‎, 11-14-2014 03:10 PM
    • Replies: 0
    • Views: 218
    11-14-2014, 03:10 PM Go to last post
  56. Study design issue: using national survey data as control group

    I'm working on a descriptive study of children who have specific health issues. Unfortunately, there is no good internal comparison group, so I'd...

    Started by adamsaa23‎, 10-31-2014 12:13 PM
    • Replies: 3
    • Views: 352
    11-13-2014, 11:07 PM Go to last post
  57. Confounder analysis for LOGISTIC regression

    Hi there, I have the following situation: I have a logistic regression analysis, in which I have 3 variables: The dependent variable- dichotomous-...

    Started by yohayohay‎, 11-09-2014 05:30 AM
    confounders, continous variable, logistic regression
    • Replies: 2
    • Views: 310
    11-13-2014, 11:01 PM Go to last post
  58. biostatistics for ordinal variable

    The study is perspective. the subject is : the effect of an intervention on antibiogram level I will have a antibiogram value at (4: for...

    Started by parisaarzani‎, 11-08-2014 03:05 PM
    biostatistics, ordinal value, repeated measure
    • Replies: 11
    • Views: 565
    11-13-2014, 04:02 PM Go to last post
  59. Statistical significance in reproducibility study

    Thanks for taking the time to read this thread and help me out! I recently carried out a reproducibility study in which 15 observers from 4 groups...

    Started by reproducibilityhelp‎, 11-09-2014 05:28 PM
    • Replies: 0
    • Views: 207
    11-09-2014, 05:28 PM Go to last post
  60. Predicted vs. actual survival

    Hi guys, I am trying to do the statistics part myself for a project which looks at ability of a model to predict survival in patients. For the...

    Started by jhm3‎, 11-07-2014 06:49 PM
    • Replies: 0
    • Views: 280
    11-07-2014, 06:49 PM Go to last post

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