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Threads 121 to 180 of 1891

# Forum: Biostatistics

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

1. ### What statistical test to use for species abundance between wet and dry season?

Sorry if this question is trivial, I have a collection of camera trap data of recorded species during the rainy season and the dry season. I am...

• Replies: 5
• Views: 3,421
01-08-2017, 02:38 PM
2. ### Temporal Distribution of Death

Dear all, I plan to conduct a study. The preliminary aim is to examine the temporal distribution of death of terminal cancer patients in hospice...

• Replies: 10
• Views: 4,515
01-03-2017, 04:40 AM

I want to add Area Under the Curve (AUC) from multiple meta analyses. AUC for each Meta analysis is given. How can I add them together?

• Replies: 6
• Views: 4,249
12-23-2016, 08:08 AM
4. ### Patterns in DNA, seperating signal from noise -- outliers?

Hello all, I'm looking at patterns in fragments of RNA. What I need to do is separate the signals from noise in Exons (small regions of DNA/RNA)....

• Replies: 2
• Views: 3,554
12-22-2016, 05:05 AM
5. ### t-test or z-test for two proportions?

We did an intervention to reduce the frequency of use of a certain type of treatment and now I want to compare the data pre vs post intervention. ...

• Replies: 3
• Views: 3,901
12-19-2016, 11:01 AM
6. ### Interpreting Odds Ratios... weird question

Hi, I sort of have a weird question. I have a basic understanding of ORs, and can interpret them, but it's never been clear to me why we...

• Replies: 6
• Views: 3,619
12-16-2016, 11:37 AM
7. ### Area under Kaplan Meier curve

There is one thing bothering me for some time: What does area under Kaplan-Meier survival curve actally represent? Is there a plausible way to...

• Replies: 0
• Views: 3,681
12-10-2016, 05:55 AM
8. ### Pooling time points to perform a Fisher test?

Hello, I am currently trying to analyse an experiment to assess if rats with cerebral malformations have a sensitivity deficit on one of their...

• Replies: 4
• Views: 3,972
12-09-2016, 03:58 AM
9. ### What kind of statistical test can be used for my data?

It is my first post on this forum so please be gentle. If it is not a proper section I would appreciate if moderator moves the thread to the correct...

• Replies: 1
• Views: 3,008
12-07-2016, 01:27 PM
10. ### How to obtain an unbiased post-stratified estimator for survival probabilities?

Suppose I have estimated the survival probabilities $\hat{S(t)}_1, \hat{S(t)}_2, \ldots, \hat{S(t)}_H$ from $H$ strata. Now I want to get an unbiased...

• Replies: 3
• Views: 3,828
12-06-2016, 11:07 AM
11. ### Why not use Kaplan Meier?

In the method described here http://dmkd.cs.vt.edu/papers/TKDE17.pdf R code implementation is provided ...

• Replies: 5
• Views: 3,121
12-03-2016, 09:56 AM
12. ### Bird Community Ecology - BACI experiment

Greetings! I'm currently trying to investigate the impact of an event on the bird community of a National Park on my country. For that I have...

• Replies: 2
• Views: 3,356
12-02-2016, 03:19 PM
13. ### How to use chi-square test correspondence between features and response in R?

There is a set of tumors,each one includes five features, which relate to one gene type result. Tumor Feature 1 ... Feature 5 Gene type 1 ...

• Replies: 0
• Views: 3,222
11-27-2016, 12:56 PM
14. ### MDS vs ANOVA / GLM methods - how and why?

Hello to all :wave: I am a new member of this forum and the reason why I ended up here is the following: like many others, I am in desperate need of...

• Replies: 0
• Views: 3,206
11-26-2016, 06:17 AM
15. ### How the estimate a smple size ?

Hi everybody; I am a PhD student, my thesis focuses on the study of reproductive health among teenagers girls . For that, I'am going to work in...

• Replies: 2
• Views: 3,146
11-25-2016, 12:15 PM
16. ### Help with linear model

Hi guys, I'm really struggling with the relevant coding for this, I'm using Rstudio. I need a Linear model with Gaussian error structure to find...

• Replies: 1
• Views: 3,769
11-23-2016, 10:51 AM
17. ### Model Selection in Survival Analysis

I'm having trouble with parametric model selection in survival analysis. I founded this sequence of steps in some presentation. This is an...

• Replies: 1
• Views: 3,541
11-23-2016, 10:44 AM
18. ### estimating start point of a production of y" -ie findx for y=0 given y values for x>0

I hope I can explain the problem clearly and its not an obvious solution. the application area is say an event (in the body) at say day=0 starts the...

• Replies: 3
• Views: 4,125
11-23-2016, 04:29 AM
19. ### Help with calculating probability?

I have a strange set of data, it was counting the number of animals entering and leaving a shelter as a 'count' of how many were in the shelter. We...

• Replies: 0
• Views: 2,484
11-22-2016, 07:55 PM
20. ### Experimental design: Gender comparison in a novel memory matrix.

Hello, I am a medical student who knows very little about biostats and would like some one to tell me whether my analysis for my research makes...

• Replies: 4
• Views: 3,232
11-22-2016, 07:55 AM
21. ### Proportional hazards and Cox Model

I'm trying to fit a Cox model, but there is some problems. I have the following variables in the model. - Group: 1, 2, ..., 9 - Sex: 1 female...

• Replies: 5
• Views: 3,444
11-10-2016, 12:42 PM
22. ### Cumulative Incidence with Confidence Intervals when using IPTW

Dear Stata users, I'm doing a time to event analysis with inverse probability of treatment weights(IPTW) estimated with propensity scores from a...

• Replies: 2
• Views: 3,668
11-10-2016, 12:01 PM
23. ### Help with setting my study!

Hi all, I'm a newbie to biostatistics and I'm trying to figure out how to set the statistical part of my final project. I'm a dentistry student and...

• Replies: 1
• Views: 2,702
11-08-2016, 09:16 AM
24. ### Parallel and subsequential diagnostic tests

Hey guys, i just ran into a problem: I am having two predictive models: Model 1: Sensitivity: 0.8 Specificity: 0.4

• Replies: 12
• Views: 3,942
11-08-2016, 02:59 AM
25. ### Dataset for statistical analysis

Dear all, I work in Rome for the Italian National Health Service (www.iss.it); I am currently working on a European clinic project called EMTICS...

• Replies: 4
• Views: 4,729
11-07-2016, 04:55 AM

I'm a general surgery resident and am conducting a quality improvement study about waste in the OR. My statistics background is limited to what I was...

• Replies: 5
• Views: 3,674
11-07-2016, 02:08 AM
27. ### Medical news story - Is this an OK way to report the stats?

I'm a medical writer covering an upcoming research paper. I'm new to the forum, so please LMK if this is not an appropriate place for my question. ...

• Replies: 2
• Views: 3,715
11-04-2016, 12:40 PM
28. ### Observed difference between two test for same patient is due to chance?

Hi, I have results from two very sensitive but different lab test trying to find pathogen in a patient sample. For some patients results from two...

• Replies: 0
• Views: 2,511
11-02-2016, 01:02 PM
29. ### Help with correct model formula for a repeated measures design

Hi there, I will really appreciate some help denoting the proper formula to fit a GLM for the following repeated measures data: I investigated...

• Replies: 0
• Views: 2,211
11-01-2016, 10:45 AM
30. ### Question about sample size penalty for looking at data mid-trial

Hi, we're running a clinical trial for a skin treatment with a medical device that has a strong effect. We are using an inter-patient control (no...

• Replies: 3
• Views: 4,400
10-29-2016, 01:08 PM
31. ### Help with regards to deciding appropriate statistical test for success criteria

Hello, I have the collective data of 35 eyes that underwent trabeculectomy surgery for glaucoma control. There is no control group, and...

• Replies: 1
• Views: 2,772
10-27-2016, 05:00 PM
32. ### Converting GEE and MIXED from SAS to SPSS

Hello, I’m trying to do data analysis with GEE and/or Mixed models but get stuck in choosing the right SPSS syntax. I have data from subjects...

• Replies: 0
• Views: 2,901
10-25-2016, 04:37 PM
33. ### Help for sample size calculation

in my prospective cohort study I will assess the serum level of a vitamin in a group of patients the normal reference serum range is 10-30 in normal...

• Replies: 1
• Views: 3,303
10-23-2016, 11:37 AM
34. ### Correlated variables in Cox model - which one is best

Hi there, I am building a Cox model. I have two variables that are different measures of the same thing and they are therefore correlated with each...

• Replies: 0
• Views: 2,697
10-23-2016, 09:27 AM
35. ### HELP with data collection methods and data analysis in quantitative research : )

I am doing a research proposal on the effect of a drug on haemorrhage growth in traumatic brain injury. My null hypothesis: TXA does not reduce the...

• Replies: 1
• Views: 2,800
10-22-2016, 12:53 AM
36. ### Appropriate statistical test for HR's comparison between 2 population

In case of 2 population, the first has HR X for the study's outcome (between the exposed and non-exposed groups), and the second has HR of Y (between...

• Replies: 1
• Views: 3,114
10-21-2016, 06:02 AM
37. ### Which statistical test to use for my data analysis

Hi everyone, Could someone help me to know which statistics should i use for my data analysis. I did my project on "personal exposure...

• Replies: 4
• Views: 2,872
10-19-2016, 05:39 AM
38. ### Recurrent Event Survival Analysis

Hi there, I'm working on a research on individuals who enter financial distress using the Cox proportional hazards model. In this case the...

• Replies: 0
• Views: 2,506
10-17-2016, 07:46 AM
39. ### Sample Size Calculation (HELP!)

Hi all, I wish someone could help me out. I am trying to estimate the sample size for a national health survey. From the previous report,...

• Replies: 1
• Views: 2,770
10-14-2016, 05:22 AM
40. ### Markov Process to estimate time until death

Are there any websites that show examples of data setup and SAS code using some sort of Markov model to estimate time until or probability of death?...

• Replies: 0
• Views: 2,832
10-05-2016, 12:14 PM
41. ### Which comparison of means test to use?

I've got myself confused about which test to use. I have done a cross sectional survey exploring the difference between pain as measured with a...

• Replies: 1
• Views: 2,480
10-04-2016, 11:14 AM
42. ### comparing sensitivity, specificity, and PPV of different cohorts-is it possible?

hello and thanks in advance for helping out! i hope that my questions will not be terribly on-profesional .. i'm trying to figure how to compare...

• Replies: 2
• Views: 2,972
10-03-2016, 11:24 PM
43. ### Poll: How do you handle subjects having very different patterns?

Good day everyone - I am curious as to what you all do in these situations. If you are running a sleep study, and you are simply using two...

• Replies: 2
• Views: 3,569
09-26-2016, 12:14 PM
44. ### Estimating main effects in a two factorial log linear model when applied to RNA-seq

Hi everybody, I'm going to apply multiDE, an R package for detection of DEG in multiple treatment conditions, on some RNA-seq time series data......

• Replies: 0
• Views: 2,670
09-16-2016, 02:29 PM
45. ### Survival analysis

Hi there, I am doing some breast cancer survival analysis on population-based registry data...I have outlined to estimate incidence trends and...

• Replies: 2
• Views: 3,519
09-16-2016, 04:20 AM
46. ### What test to use?

Hi all, I am new to statistics. Now, I am doing a research but I don't know which test to use. Basically, I have four groups with both positive...

• Replies: 1
• Views: 2,713
09-14-2016, 02:54 PM
47. ### R caret package: problems understanding the functions in confusionMatrix

Hey, I earlier posted about the problematic interpretation of PPV (positive predictive value). As there seems to be no easy solution for that I...

• Replies: 2
• Views: 3,244
09-13-2016, 01:44 AM
48. ### Analysing pre- and post-treatment lactate curves

Good morning all, Has anyone got experience with analysing lactate against power curves? I have pre- and post-treatment lactate curves for 10...

• Replies: 0
• Views: 2,633
09-12-2016, 03:21 AM
49. ### [SPSS - post hoc analysis and Logistic regression] When the result don't line up

I'm a medical student doing his research interneship. We're currently investigating if there's a link between motoric and mental outcome and MRI...

• Replies: 0
• Views: 3,053
09-08-2016, 05:34 AM
50. ### How to evaluate significance.

Hi, I have 58 samples and an enrichment analysis was done to each of them. So for each sample I have a list of enriched terms. I've collected the...

• Replies: 0
• Views: 2,457
09-06-2016, 11:14 AM
51. ### ROC curve cutoff not significant, but it works

I'm dealing with a numerical variable and its prognostic significance in a sample of cancer patients. I'm trying to find an optimal cutoff point for...

• Replies: 4
• Views: 3,188
09-04-2016, 01:14 PM
52. ### How to analyze this data

Hello, I need guidance in analyzing the outcome. I have 4 independent variables, and 2 dependent variables. The sample size is ~600. I...

• Replies: 1
• Views: 2,283
09-02-2016, 03:46 AM
53. ### Help deciding paired vs unpaired t-test

Hi, I am analyzing an experiment in which protein levels were examined in two different strains of bacteria. Lets call them A and B. Three...

• Replies: 2
• Views: 2,487
09-01-2016, 02:19 PM
54. ### Help decide on appropriate test for experiment design

Hello - new to the forums here! I work in cell biology and a colleague and I are designing an experiment to determine the appropriate...

• Replies: 5
• Views: 3,007
08-30-2016, 04:01 PM
55. ### Positive predictive value of biased data

Hey, I am currently dealing with prediction of binary data due to structural alerts. This means if a substructure is within the query structure it...

• Replies: 2
• Views: 2,415
08-30-2016, 01:21 AM
56. ### Matched Groups Statistics

Hello all hope this is the right thread for the question and that someone will be able to help me out :confused: I have created a propensity...

• Replies: 2
• Views: 3,073
08-29-2016, 01:42 PM
57. ### I need advice on Fisher's exact test

I recently submitted a paper and in my study, I wanted to see if there is an association between a gene mutation and the absence/presence of the...

• Replies: 4
• Views: 3,305
08-29-2016, 03:50 AM
58. ### calculate p value significance

How to calculate p value significance for the following? We educated 334 individuals over the age of 50 about cancer. 87 (26.05%) of them made...

• Replies: 2
• Views: 2,669
08-27-2016, 06:48 AM

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