Clinical trials are studies designed to test the safety and efficacy of new clinical interventions such as drugs or medical devices.
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Converting confidence interval around percent change into confidence interval around final value
I have clinical trial data that I'm trying to extract from a publication. I need the final value and the standard deviation around the final value. What I have is the initial value, initial value's ...
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1answer
95 views
How to calculate the population survival probability in a two stage randomized clinical trial?
I am trying to reproduce a paper on two stage randomized clinical trials. In these clinical trials, a patient is randomized to either of the maintenance therapies $B_1$ or $B_2$ upon their remission ...
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2answers
100 views
Book recommendations for biostatisticians in CRO and pharmacy
I would like to learn more about the work and statistical methods performed as biostatistician in pharmaceutical companies and clinical research organizations.
It seems the book "Essential Medical ...
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0answers
65 views
Best practice when analysing placebo-controlled within-subject designs
I would like to analyse data from a placebo-controlled within-subject design. For every subject a numeric outcome variable (Y) was measured twice - once following administration of a drug and once ...
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1answer
103 views
Normalizing when doing count statistics of patient numbers on different arms of a clinical trial
I'm looking at clinical trial data where there are various numbers of patients on different arms (A, B, C, D). All arms receive a drug that is known to cause a toxicity, but some arms receive an ...
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1answer
233 views
Interpretation of results in non-inferiority study
I need some help interpreting some results from a non-inferiority study. The primary endpoint for assessment of non-inferiority is the change from baseline in Power of Attention Score. The study is ...
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1answer
56 views
Books on designing clinical trials for psychotherapy research
I'm designing a clinical trial that will evaluate a behavioral therapy against a control condition, and I'm looking for some good texts on this topic. There are a lot of books on clinical trials in ...
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2answers
1k views
Repeated measures ANOVA for two different groups
I have conducted a clinical trial using two groups with two different treatment modalities. I have measured different physical and biochemical parameters (e.g pulse, systolic blood pressure, serum ...
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1answer
454 views
How to calculate sensitivity, specificity, and odds ratio?
I am trying to calculate sensitivity, specificity, and odds ratio of a data set, they are numerical values of percentages from 0% to 100%. How should I do the calculation?
Wikipedia has the formula:
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2answers
1k views
How to construct a 95% confidence interval of the difference between medians?
My problem: parallel group randomized trial having a very right-skewed distribution of the primary outcome. I do not want to assume normality and use normal-based 95% CIs (i.e. using 1.96 X SE).
I am ...
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2answers
278 views
Sample size for clinical trials, when effect size is predicted
How should I calculate sample size for a clinical trial when I need a power of 80% and I predict an effect size to be at lest 0.5? do I need to estimate the mean of outcome as well?
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48 views
Clinical trial design
I have a clinical trial phase 2 3 stage that I need a design for:
3 groups of 12 blood transfusion done at different Hemoglobin levels. It is not a dose escalation study because the transfusion is the ...
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112 views
Objections to randomization
In Clinical trials - a methodologic perspective, Steven Piantadosi writes (ch.13, p. 334):
In Chapter 2, I noted the objections to randomization by Abel and Koch (1997) and Urbach (1993), and ...
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50 views
What statistics is used in Clinical Testing ( in Pharma industry) [closed]
I want to know what kind of statistical methods / techniques are used in clinical testing of drugs/treatment.
The clinical studies are done by clinical research organizations. They gather the data ...
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2answers
1k views
Where to find raw data about clinical trials?
I wish to use raw data about clinical trials for the end year examination of my master students. These data could deal with any kind of molecule as long as the trials were complete (Phase 1 to 4).
Do ...
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1answer
157 views
How should one control for group and individual differences in pre-treatment scores in a randomised controlled trial?
Andrew Gelman, in the book he wrote with Jennifer Hill, states in Chapter 9, (section 9.3), on page 177:
It is only appropriate to control for pre-treatment predictors, or, more generally, ...
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1answer
184 views
How does the size of a dataset affect confounding in both randomised trials and observational studies?
I have heard that larger sample sizes in randomised trials lead to a smaller possibility of confounding.
Why is this true in the case of randomised trials?
Also, how does sample size of an ...
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2answers
219 views
When using stratified randomization in a RCT, how many envelopes per stratum should be prepared?
If one considers a hypothetical RCT, say a total sample size of 300, separated into three strata based on surgical procedure (open surgery, closed surgery, or combined procedure). Blocking in groups ...
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1answer
52 views
Correlating various diagnoses with amount of weight gained
I have a processed dataset where patients took a medication and gained a varying amount of weight. In addition, any ICD9 diagnoses the patients have received while being monitored are recorded. I'd ...
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2answers
112 views
Analyzing treatment effect with possibly flawed control data
I've got some rather messy data from a natural experiment. A number of subjects were measured (the measurements were hopefully-Poisson distributed counts and associated offsets), placed on a ...
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1answer
99 views
Pre and Post, treated and un treated but from same subject
A treatment was given to one hand of a subject, and a single outcome metric is measured for both hands, twice pre and several times post treatment.
What is best practice for assessing effectiveness ...
5
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1answer
522 views
How to extract data from published articles (RCTs) to do a meta-analysis?
I am doing a meta analysis for the first time and have a few basic questions regarding statistical analysis.
Let's say I have one study where the primary outcome (thrombosis) in the 2 treatment ...
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1answer
579 views
Covariate Adjusted Logistic Regression (“Adjusted Analysis”)
I am trying to find some help with something that is called an "Adjusted Analysis" (or also Covariate Adjusted Logistic Regression); a typical response has been that I might just want multivariable ...
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1answer
284 views
How to handle multiple comparisons in a three-arm clinical trial?
I have 3 arms in a trial. I want to compare results of a survey before during and on completion of a treatment. Data is not normally distributed. What test should I use?
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1answer
153 views
Does significance test make sense to compare randomised groups at baseline?
Many randomised controlled trial (RCT) papers report significance tests on baseline parameters just after/before randomisation to show that the groups are indeed similar. This is often part of a ...
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2answers
426 views
When is a randomised controlled trial (RCT) balanced?
I believe that for ANOVA unbalanced means unequal groups. But for randomised controlled trials unbalanced seems to mean something like groups of different characteristics despite randomisation. So in ...
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5answers
766 views
Why is bias affected when a clinical trial is terminated at an early stage?
An interim analysis is an analysis of the data at one or more time points prior the official close of the study with the intention of, e.g., possibly terminating the study early.
According to ...
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1answer
426 views
Overall type I error when repeatedly testing accumulating data
I have a question about group sequential methods.
According to Wikipedia:
In a randomized trial with two treatment groups, classical group sequential testing is used in the following manner: If n ...
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2answers
177 views
In relation to clinical trials, what is clinical reasoning in contrast to statistical reasoning?
I read Clinical Trials, a Methodologic Perspective (S. Piantadosi) as I was suggested by one of you.
According to the author:
A trialist must understand two
different modes of thinking that
...
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1answer
583 views
Building Cox Model using forward likelihood-ratio testing - Appropriateness of adding continuous variables to model?
I am constructing Cox models that predict survival in a clinical trials cohort.
After speaking to our statistician (who is away at the moment, hence this post), I was advised to take a forward ...
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1answer
123 views
Book on designing clinical trials in oncology
I would like to have a good idea on how to design clinical trials in oncology. In that issue, I am looking for a compact book that could give me a good overview, with the emphasis on statistical ...
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4answers
18k views
What is the difference between effectiveness and efficacy in determining the benefit of therapy 'A' on condition 'B'?
The context of this question is within a health framework i.e. looking at one or more therapies in the treatment of a condition.
It appears that even well respected researchers confuse the terms ...
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2answers
5k views
Best practice when analysing pre-post treatment-control designs
Imagine the following common design:
100 participants are randomly allocated to either a treatment or a control group
the dependent variable is numeric and measured pre- and post- treatment
Three ...
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3answers
314 views
How to detect which one is the better study when they give you conflicting results?
You so often come across in the press various studies that conclude directionally opposite results. Those can be related to the testing of a new prescription drug or the merit of a specific nutrient ...
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4answers
495 views
Good text on Clinical Trials?
I'm an undergraduate statistics student looking for a good treatment of clinical trials analysis. The text should cover the fundamentals of experimental design, blocking, power analysis, latin squares ...
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1answer
142 views
Heterogeneity with two studies
With data from two centres I want to account for potential heterogeneity or confounders between two centers. So the analysis will initially be stratified by clinical center and a chi square test ...
