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# Forum: Biostatistics

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

1. ### 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...

• Replies: 2
• Views: 5,509
01-22-2015, 11:15 AM
2. ### 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...

• Replies: 0
• Views: 1,364
01-22-2015, 04:55 AM
3. ### 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...

• Replies: 5
• Views: 1,590
01-21-2015, 04:49 AM
4. ### 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...

• Replies: 0
• Views: 1,006
01-20-2015, 12:23 PM
5. ### 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...

• Replies: 0
• Views: 1,499
01-20-2015, 06:40 AM
6. ### 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...

• Replies: 0
• Views: 1,247
01-19-2015, 11:13 AM
7. ### 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)...

• Replies: 3
• Views: 1,922
01-19-2015, 06:32 AM
8. ### [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). ...

• Replies: 0
• Views: 1,246
01-16-2015, 08:37 AM
9. ### [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...

• Replies: 1
• Views: 1,272
01-15-2015, 08:41 PM
10. ### 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...

• Replies: 1
• Views: 2,544
01-14-2015, 06:56 PM
11. ### 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...

• Replies: 1
• Views: 1,445
01-14-2015, 03:14 PM
12. ### 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...

• Replies: 0
• Views: 1,334
01-13-2015, 09:33 AM
13. ### 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...

• Replies: 0
• Views: 1,608
01-12-2015, 05:04 AM
14. ### 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...

• Replies: 0
• Views: 2,735
01-11-2015, 01:11 PM
15. ### 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...

• Replies: 2
• Views: 1,610
01-09-2015, 03:56 AM
16. ### 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...

• Replies: 2
• Views: 1,921
01-08-2015, 01:22 AM
17. ### 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...

• Replies: 0
• Views: 2,060
01-07-2015, 05:30 PM
18. ### 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...

• Replies: 2
• Views: 2,771
01-07-2015, 05:13 PM
19. ### 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...

• Replies: 1
• Views: 1,697
01-07-2015, 02:56 AM
20. ### 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 ...

• Replies: 1
• Views: 1,400
01-06-2015, 09:48 PM
21. ### 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 ,...

• Replies: 0
• Views: 3,234
12-29-2014, 06:17 AM
22. ### 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...

• Replies: 1
• Views: 1,904
12-24-2014, 09:44 AM
23. ### 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...

• Replies: 5
• Views: 9,563
12-22-2014, 10:21 PM
24. ### 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...

• Replies: 3
• Views: 2,815
12-21-2014, 04:40 PM
25. ### 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...

• Replies: 1
• Views: 1,777
12-21-2014, 09:03 AM
26. ### 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...

• Replies: 2
• Views: 1,672
12-19-2014, 05:54 AM
27. ### 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...

• Replies: 0
• Views: 1,255
12-18-2014, 04:24 PM
28. ### 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...

• Replies: 0
• Views: 1,527
12-16-2014, 05:20 AM
29. ### 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...

• Replies: 23
• Views: 16,625
12-15-2014, 06:28 PM
30. ### 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...

• Replies: 6
• Views: 2,899
12-13-2014, 05:46 AM
31. ### 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...

• Replies: 5
• Views: 1,734
12-12-2014, 07:57 PM
32. ### 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...

• Replies: 1
• Views: 2,044
12-12-2014, 05:12 PM
33. ### 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...

• Replies: 6
• Views: 2,041
12-10-2014, 01:54 AM
34. ### 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...

• Replies: 3
• Views: 2,130
12-09-2014, 08:00 AM
35. ### 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...

• Replies: 0
• Views: 1,420
12-07-2014, 06:13 AM
36. ### 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...

• Replies: 0
• Views: 1,237
12-05-2014, 11:07 AM
37. ### 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...

• Replies: 4
• Views: 1,929
12-05-2014, 04:17 AM
38. ### 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...

• Replies: 0
• Views: 1,304
12-04-2014, 12:19 PM
39. ### 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...

• Replies: 0
• Views: 1,529
12-04-2014, 05:32 AM
40. ### 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...

• Replies: 3
• Views: 6,388
12-02-2014, 09:18 AM
41. ### Should I use a two sample or paired t.test?

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

• Replies: 5
• Views: 1,833
11-28-2014, 07:40 AM
42. ### 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...

• Replies: 0
• Views: 1,293
11-28-2014, 06:19 AM
43. ### 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...

• Replies: 2
• Views: 1,746
11-27-2014, 01:03 PM
44. ### 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...

• Replies: 3
• Views: 1,419
11-18-2014, 10:53 AM
45. ### 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...

• Replies: 0
• Views: 1,198
11-14-2014, 03:10 PM
46. ### 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...

• Replies: 3
• Views: 2,034
11-13-2014, 11:07 PM
47. ### 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-...

• Replies: 2
• Views: 1,697
11-13-2014, 11:01 PM
48. ### 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...

• Replies: 11
• Views: 2,547
11-13-2014, 04:02 PM
49. ### 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...

• Replies: 0
• Views: 1,459
11-09-2014, 05:28 PM
50. ### 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...

• Replies: 0
• Views: 1,190
11-07-2014, 06:49 PM
51. ### Comparing blood levels at 2 time points between 2 groups

Hey everyone, I'm incredibly inexperienced when it comes to biostatistics. For my bachelor's thesis, I need to do statistical analyses, and I want...

• Replies: 1
• Views: 1,673
11-07-2014, 09:28 AM

Hello, Somebody knows what is the method to calculate an age-adjusted cumulative incidence for a clinical event? Also, could you tell me if...

• Replies: 1
• Views: 1,433
11-06-2014, 04:32 PM
53. ### Is this linear mixed effect repeated measures?

I'm looking for some clarity on the following. This experiment tested the null hypothesis that 2 methods for measuring the length of an animal...

• Replies: 0
• Views: 1,305
11-04-2014, 09:13 PM
54. ### summarizing health indicators by facility

Hi! A bit of background about the current issue: We're looking at a set of 6 indicators (simple binary variables) aggregated at a facility...

• Replies: 0
• Views: 946
11-04-2014, 10:19 AM
55. ### repeated measurements - ANOVA, friedmann's test or kruskal wallis?

Dear all, I am a junior doctor getting involved in medical statistics, of which my knowledge is very preliminary. The problem I face is the...

• Replies: 0
• Views: 1,103
10-29-2014, 04:25 PM
56. ### Noob question

why when modeling do some variables have significant p values yet they are not included in the model ? I was doing a cox regression model and...

• Replies: 7
• Views: 1,679
10-29-2014, 03:05 PM
57. ### Fisher test or interaction terms to determine if 2 groups are different

Hi, I split my sample in 2 groups, participants with condition +M and participants without the condition -M. I calculated correlations and beta...

• Replies: 3
• Views: 2,028
10-29-2014, 01:31 PM
58. ### Identical continouous dependant variables vs. unique independent variables?

Hi guys, I'm having an issue re: the statistical test I should be using in research I am undertaking. Let's say I have a study population of...

• Replies: 2
• Views: 1,740
10-29-2014, 08:39 AM

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