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Threads 481 to 540 of 1891

# Forum: Biostatistics

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

1. ### Block desing with several datapoints

Hey, I'm a PhD students and confronted with the following problem, hoping someone can give me an advise. For my research I had to use a more...

• Replies: 0
• Views: 1,320
04-02-2015, 08:57 AM
2. ### Total complications in both groups

Hi, I have the following question: In my study I compare two kinds of surgery options. Group A has 9 patients and group B has 6 patients. When...

• Replies: 9
• Views: 1,779
04-01-2015, 01:04 PM
3. ### Sample size calculation for non-inferiority and superiority

Dear all, I am little bit confused with dual statements which I read in the literatures and books. Some says that Non-inferiority studies requires...

• Replies: 4
• Views: 1,695
03-27-2015, 09:48 PM
4. ### Comparing rates of hospital episodes in different groups

Hi there, I'm trying to compare the rates of hospital admissions in different groups. For example: 200,000 people live in the local area, and...

• Replies: 6
• Views: 1,502
03-27-2015, 11:32 AM
5. ### Discretization of a continuous variable

He guys, I'm analyzing a research regarding patients and their risk factors for developing a certain side effect. If i enter age as a continous...

• Replies: 1
• Views: 1,145
03-26-2015, 06:20 AM
6. ### Three way anova for repeated measure

Hi all, I am struggling with how to properly fit a three way anova using STATA. It keeps giving me this error message "could not determine...

• Replies: 5
• Views: 1,828
03-25-2015, 07:33 AM
7. ### Futility analysis sample size

Hello, I have been asked to determine the sample size needed to demonstrate futility in a small study. I suggested going the "traditional route" and...

• Replies: 2
• Views: 2,505
jcr
03-24-2015, 10:10 AM
8. ### One or Two Way ANOVA?

Hi all, Just had a quick question regarding whether or not I should be using a one or two way ANOVA to see the effect of caffeine on heart rate....

• Replies: 4
• Views: 1,065
03-23-2015, 11:10 AM
9. ### Comparing proportions

I am planning ahead before starting an experiment and want to be sure that I can analyze the results statistically. I have two related questions,...

• Replies: 1
• Views: 1,477
03-23-2015, 09:22 AM
10. ### types of chi-square statistics

:) hi all I want to know types of Chi-square statistics and their applications. Such as Pearson x2 and mantel-haenzel x2 and x2trend and ... .

• Replies: 2
• Views: 1,686
hol
03-20-2015, 01:35 AM
11. ### Comparing Measured and Predicted body Mass - Can I use the T-Test

I have measured the body mass (Mb) of several wildebeest in kg. I have also measured other parameters including Girth (G), Length (L) and shoulder...

• Replies: 3
• Views: 1,792
03-17-2015, 06:45 AM
12. ### Fat percentage affecting diet

Need some help with some biostats. Studying for a final right now. I think i need to do a one-way anova and a post hoc comparison. I also need a full...

• Replies: 0
• Views: 1,423
03-16-2015, 08:55 PM
13. ### Comparing two %, what test can I use?

Good afternoon forum fellows, I am currently conducting a prospective research study at my hospital. I haven't used my stats skills in awhile and...

• Replies: 3
• Views: 1,406
03-16-2015, 07:49 PM
14. ### Range, does it matters ?

Hello I am slightly confused about something. I will try to illustrate. Let's say that if one takes a medication to treat a condition, the...

• Replies: 3
• Views: 1,367
03-16-2015, 03:18 AM
15. ### Mantel's Chi 2 test - how to perform

Hello dear users, I have a question about Mantel's Chi 2 test and you are my last hope :). I want to perform Mantel's Chi 2 in SPSS but cant find...

• Replies: 3
• Views: 1,545
03-14-2015, 02:20 PM
16. ### Comparing means with zero-inflated data in SPSS

Hi everybody, I whish to know how to compare means with zero-inflated data. I tried to perform an ANOVA test but obviosuly it's impossible since...

• Replies: 0
• Views: 1,659
03-12-2015, 12:09 PM
17. ### T test on whole sample or on averages

Background: Consider the following experiment: There are two groups of subjects, Group A have been treated with a drug that affects the muscle...

• Replies: 3
• Views: 1,087
03-12-2015, 06:25 AM
18. ### Repeated measures in a GLM, do I need to use a GLMM?

Hi guys, So I have finished an experiment where I had 11 cages of mice building nests with 3 different materials. Each cage was given a material...

• Replies: 1
• Views: 1,502
03-10-2015, 02:30 PM
19. ### what stats to use?

Dear All, As I am not experienced in stats I would like to ask for some stats suggestions for a study. study one: control impact with one...

• Replies: 0
• Views: 1,240
03-10-2015, 11:56 AM
20. ### Survival Analysis - Rate covariates

hi all! I'm not too experienced with survival analysis, so I'm hoping to get some feed back regarding our design / study: Start Date: Date...

• Replies: 0
• Views: 1,098
03-05-2015, 11:51 AM
21. ### Survival curve from competing risk analysis

I conducted a competing risk analysis of time-to-event data and produced graphs for the cumulative incidence functions. The investigator that I am...

• Replies: 2
• Views: 1,296
03-05-2015, 09:48 AM
22. ### How to calculate the confidence interval of the ratio of two means (paired data)

Hi there, I am writing a systematic review and need to calculate the 95% confidence intervals of the ratio of means from whatever the clinical...

• Replies: 7
• Views: 3,738
BGM
03-05-2015, 01:32 AM
23. ### Regression vs. t-test

Hello all, I have this small study, and I am wondering how to analyze it. I have a measure X taken before some event, and after for every...

• Replies: 6
• Views: 1,860
03-04-2015, 02:53 PM
24. ### Need help

I have 3 groups, out of these 3, 1 is the control group. other two i have studied the effect of two modes of exercise. so i have before and after...

• Replies: 2
• Views: 1,569
03-04-2015, 12:28 PM
25. ### 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...

• Replies: 5
• Views: 3,317
03-02-2015, 11:08 AM
26. ### Clustering sites to compare with cluster of species similarity (dendrogram?)

Hi, I hope someone can help me here. I kind of have something specific in mind to analyze parts of my data, but I am not sure how to get there. I...

• Replies: 2
• Views: 1,756
02-27-2015, 01:06 PM
27. ### Calculating life expectancy for cancer patients

Hi all I have been asked to use life table analysis to calculate life expectancy for cancer patients from birth. I am comparing 3 different...

• Replies: 0
• Views: 1,414
02-26-2015, 03:56 AM
28. ### How to calculate the covariance of two paired, continuous measurements

Hi there, Is it possible to calculate the covariance of two paired, continuous measurements in a before-after clinical trial design without the...

• Replies: 0
• Views: 1,007
02-25-2015, 11:43 PM
29. ### Retrospective review analysis questions

Hello! I am new to this forum. Thank you in advance for any help you can give!:wave: I am doing a prelim analysis for a pilot study I have...

• Replies: 3
• Views: 1,539
02-25-2015, 05:46 PM
30. ### outcomes of surgery

Can someone point me into the right direction I have a database of patients who have had surgery which is deemed a success or not(0,1). Each...

• Replies: 3
• Views: 1,814
02-24-2015, 03:47 PM
31. ### Chi square vs Mcneamar's test

Hello I have a cohort study where a cohort of subjects with a specific characteristic has been matched to a control group according to age (+/ 3...

• Replies: 3
• Views: 2,027
02-23-2015, 11:43 AM
32. ### Formula for S shaped curve given specific values

I need to derive a formula that will give me an S-shaped curve, such as this one: The x-values would go from 0 to 250 and the y-values from 0 to...

• Replies: 3
• Views: 2,506
02-19-2015, 01:52 PM
33. ### Sample size calculation in clinical trial

Could you please help me understand how did they calculate the sample size in this randomized trial ? It is a randomized trial comparing the use...

• Replies: 0
• Views: 2,556
02-12-2015, 11:29 AM
34. ### Cmax as covariate in mixed model?

Hello, I am involved in a study looking at drug effects on HR. We have one treatment and one placebo group, and are testing patients once/week for 8...

• Replies: 0
• Views: 1,091
jcr
02-11-2015, 10:08 PM
35. ### Comparison of two variables from one sample set

I have collected two measurements from a set of 100 tumour biopsies. One measurement is the percentage mutant allele of a particular mutation. The...

• Replies: 2
• Views: 1,374
02-11-2015, 03:49 PM
36. ### Which test/study to use?

Hey Guys, I was wondering if I could get some help. Lets say you have a group of patients who are positive for a disease based on the gold...

• Replies: 6
• Views: 1,766
02-10-2015, 03:48 PM
37. ### How many people have the disease based on the prevalence?

Hi, I know that Prevalence=(persons with a given health indicator during a specified time period/ population during the same time period) X...

• Replies: 4
• Views: 1,179
02-10-2015, 12:19 PM
38. ### Trouble writing results

I have a lot of trouble writing up results in text. At present I have a one table which has descriptive statistics and univariate analyses (i.e....

• Replies: 0
• Views: 895
jle
02-10-2015, 12:55 AM
39. ### One-Way ANOVA and tongue testing

I have a pretty basic question about using a one-way ANOVA. I am performing an oral tribology experiment on pig tongues which basically means I am...

• Replies: 2
• Views: 1,638
02-06-2015, 02:07 PM
40. ### comparing results of 2 chi2 tests, + proper graphing

Hello, i was wondering what the appropriate test would be for comparing the results of 2 chi square tests. For example, if I did one experiment...

• Replies: 0
• Views: 1,309
02-06-2015, 01:48 PM
41. ### Test validity

Hello friends, I'm really new at this, I'm in high school, and wanted your help to know how does someone check or calculate if a test is actually...

• Replies: 10
• Views: 2,815
02-05-2015, 01:13 AM
42. ### Calculating & Interpreting Cohen's D Effect Size

Dear all, Im new to effect size & am struggling with some of the calculations, hence would like to seek some thoughts / advice. 1) Im calculating...

• Replies: 12
• Views: 6,676
02-04-2015, 06:58 PM
43. ### What statistical test to use ?

For example :- I have a drug of two different doses (low dose and High dose) and i want to test this drug of two different doses on 3 age groups of...

• Replies: 2
• Views: 2,472
02-03-2015, 12:04 PM
44. ### 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...

• Replies: 4
• Views: 1,746
02-03-2015, 03:55 AM
45. ### Permanova using adonis, comparing a focus group with the rest (all other groups)

Dear all I would like to compare the community composition of a certain region, against the composition of the neighbouring regions. This is an...

• Replies: 0
• Views: 1,151
02-03-2015, 02:27 AM
46. ### Confidence intervals: normal vs t-distribution (central limit theorem)

Hi all! We did a serological survey for a disease taking 300 samples in a population of 50 000. If our sample mean gives a 2% prevalence. How...

• Replies: 2
• Views: 1,797
02-02-2015, 09:40 AM
47. ### IRR over time for different areas?

Hi all, I'm not quite sure why I'm getting confused about this, but I am! So I have 3 different areas and my study period is over 17 years with...

• Replies: 0
• Views: 1,280
02-01-2015, 10:59 PM
48. ### 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...

• Replies: 2
• Views: 1,263
01-30-2015, 04:04 AM
49. ### 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...

• Replies: 2
• Views: 1,501
01-30-2015, 03:46 AM
50. ### 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...

• Replies: 0
• Views: 2,049
01-29-2015, 05:58 PM
51. ### 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...

• Replies: 1
• Views: 1,408
01-28-2015, 05:43 PM

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