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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Adjustable sample size in clinical trial

Most clinical trials I see have a fixed sample size. In some cases they have prior data that allows estimating the effect size and the variance or distribution of values, and calculate the sample ...
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11 views

Analysis of PValues Matrix

in clinical environment I'm setting up a model to identify fraudolent behaviours from specific sites, calculating for each site some aspects that could lead to a p-value (this approach is based on a ...
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20 views

Analysis of pre-post data when 2 treatments given serially to same subjects

I have following data from a cross-over trial where subjects were given 2 types of treatments separated by a washout period. For each treatment measurement was made in pre and post treatment period. I ...
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24 views

Is conditional logistic regression appropriate for comparing costs between treatments?

I am looking at previous reports done by a previous staff member comparing 2 treatments - lets call them treatment A and B for epilepsy and the total costs for a matched population. For instance the ...
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1answer
16 views

How to scale up mean/variance and confidence interval of clinical trial for whole population

In a clinical trial I have 1000 patients with disease A. Their mean treatment cost is 1000$ per patient with a 95% confidence interval of [900;1100] for example. The whole population of country X is ...
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31 views

Per-protocol analysis in a clinical trial

I am doing data analysis on a clinical trial. I know the rule here is to do analysis according to intention to treat (ITT, ie. analyse according to the group to which the individuals were randomised). ...
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25 views

Regression analysis for a clinical trial with repeated measures

I am currently working with a dataset that was collected from a depression study at baseline and 6 months for a group of 60 participants. Also these participants are divided into 4 groups based on ...
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1answer
18 views

Time to event with a discrete number of time points

I'm planning a clinical study, in which my desired primary outcome is time to event. My new treatment is non-inferior to the current one in it's therapeutic abilities, however it makes an impact much ...
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12 views

Interim analysis and CI

A trial was planned and designed to be a single arm trial (one group), and the sample size was calculating using a confidence interval to achieve some accuracy in the estimation of the unknown ...
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24 views

Outcome Results - Mean Change & Standard Error - Missing Standard Deviation

The results of a clinical trial are given as "Mean Change", together with a "Standard Error", also the "Mean Differences" of the Intervention and Control are given, together with 95% Confidence ...
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14 views

Expected p-values from a series of trials

I'm looking at this toxicology study (http://www.sciencedirect.com/science/article/pii/S0041008X1500085X). The study has a negative control group, a positive control group and three treatment groups ...
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2answers
83 views

Change scores as outcome measurements in clinical trials

I am performing a Meta-Analysis about a mental disease, comparing intervention vs. control groups and try to extract outcome results from published study papers. In some clinical randomised trials ...
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0answers
18 views

Test that does not based on sufficient statistics [closed]

In the context of adaptive clinical trials, inverse normal method/test was addressed as not based on sufficient statistics, while sequential tests do. Is it because in adaptive design, the test is not ...
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17 views

Permuted block design Wilcoxon sum rank test

I need to do a Wilcoxon rank sum statistic for some data with a permuted-block with 2 blocks of size 6. However, I'm confused how we deal with the permuted-block randomization. My book says When ...
2
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0answers
62 views

Power analysis for logistic regression

I have to deliver a statistical analysis plan that will have to be approved by an ethic commettee before I could start a clinical trial. I usually deal with different kinds of tests, whose power ...
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0answers
44 views

R Packages for rank-preserving structural failure time model (RPSTM)

I have a randomized clinical trial data that has high percentage(30-40% in both arms) switching over to a different treatment regimen. By browsing through some literature, I am inclined to perform ...
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1answer
27 views

Why is screening test more concerned about sensitivity while diagnostic test is more concerned about specificity?

Screening Test : A large number of apparently healthy people are tested to identify those who are at a risk of the condition or disease. ...
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27 views

Randomization for multi-site clinical trial, screen failures

Two questions about appropriate randomization procedures for a small two-armed trial at 3 sites. About 100 participants total, evenly split between study arms. First, we are concurrently enrolling ...
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1answer
44 views

Sample size calculation for clinical trial

I am facing a problem regarding sample size calculation of clinical trial. Currently a drug is used at 2.5 mg for adult and ...
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1answer
25 views

Can we say a control / placebo group exists in a complex intervention?

In the case of something like acupuncture (as an example), it is very hard to set a placebo group or control group, since this therapy is not like taking drugs. Lets say if the needle is not in the ...
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1answer
69 views

ANOVA or ANCOVA

I have to analyze a study where 2 treatments (t1 and t2) were used to control blood sugar levels. The 't2' is a new treatment which is being compared with an old established treatment 't1'. I have a ...
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18 views

Classification with two different dataset

I am working on a cancer classification model.Task is ,I am initially given a data set of 500 people and 1000 features.These people are given some kind of treatment(say Treatment 1). Some people are ...
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1answer
63 views

Randomization software/service for clinical trial

I need a software/web-based system for the clinical randomization. This software/service should have the capabilities for handling stratification, multiple centers and block. The sample size of ...
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1answer
72 views

RCT baseline controls that do not match outcome measures

Does anyone have any input on whether it is ok to use baseline measures as control variables in a randomized controlled trial (RCT) if they are not exactly the same as the outcome measures? I.e., if ...
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1answer
108 views

Bayesian inference of a clinical trial for clinicians

I am a clinician who is more adept than average at interpreting clinical trials in a frequentist manner. At this point, interpreting a trial as a frequentist has kind of become a procedure: check ...
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39 views

Type-1 Error of the Two-Stage Design

Background on Two-Stage Designs In clinical trials, we are often interested in the response rate $p$ for an experimental treatment. In a typical trial, we might expose $n$ patients to the treatment ...
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54 views

power for estimating treatment heterogeneity in RCT

Could someone point me to a good resource for estimating power for detecting treatment heterogeneity via interactions in MR? Let's assume that individuals will be randomized to two study arms. To ...
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1answer
24 views

A clinical test incorrectly identified 50/150 false positives and 23/150 false negatives.Calculate the number of true positives and true negatives

Was wondering if anybody could explain how I can calculate the answer. Would be much appreciated.
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132 views

Linear Mixed Model for Longitudinal Data: Continuous vs. Discrete Time Parameter

I would like to conduct a power analysis for a linear mixed model with fixed effects for Treatment (two levels) and Time (four ...
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66 views

Power Calculation - Calculation of Absolute Difference

I've been asked to undertake a power calculation because the regular statistician is not available. I am calculating power for a trial where the endpoint will be a percentage of patients not ...
5
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1answer
114 views

Statistical tests for comparing a skewed clinical sample

I recently surveyed 350 low-income families -- they were randomly split into two groups: control and treatment. One of the variables I am very interested in is the amount of savings of each family. ...
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2answers
56 views

How does missing data affect analysis of clinical trials?

I was helping a friend with some problems for a clinical trials administrations course they are taking, most of it was simple statistics the last question was a little more tricky. We got the answer ...
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1answer
32 views

Randomisation for 2 site clinical study

If I want to conduct a randomised study in 2 sites comparing two clinical treatment arms, and every site is expected to include 60-80 patients, is it acceptable to randomise every new patient with ...
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2answers
89 views

Clinical trials significance

I have been a studying high energy physics (HEP) for the last few years but I recently started working on a project in medical imaging. I have been a little surprised (not entirely I was aware that ...
3
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1answer
136 views

Can I use bootstrapping to evaluate the effectiveness of a clinical intervention on a small sample?

I am doing an MSc in occupational therapy, which is concerned with evaluating how effective an occupational therapy intervention is on increasing individual's with learning disabilities daily living ...
0
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1answer
90 views

Dealing with dropping non-responders in clinical trials

I'm wondering what are some good approaches for analyzing trials where non-responders are dropped out at some set point. This is not my field, so I may be unaware of standard things! Let's say there ...
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39 views

Estimating absolute difference between two conditions

A clinical trial examines the effect of two treatments upon lung function. Patients in each group contribute data at baseline and at the end of the trial. Baseline data are provided for each group ...
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207 views

Hypothesis testing with a response scale of “1, 2, 3, 4, or not applicable”

Let's imagine I'm testing a new drug that purports to reduce the effect of a hangover when the drug is administered shortly before an episode of heavy drinking. On Friday night, I stake out the ...
4
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2answers
69 views

Methods for randomly allocating people between active and placebo in clinical trials

I'm looking for a way to allocate people to either group A or B. Data for the study group has 3 main variables: Age 65-90 Male or Female APOE + or APOE – (this is a blood test) I ...
3
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0answers
84 views

stepped wedge and additive intervention effects

Let's say we want to randomize 400 caregivers to a parenting intervention or a wait-list control group. But we also want to look at a program variation for a sub-sample of caregivers of children with ...
4
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1answer
366 views

Rolling out trial in phases, but not stepped wedge

Update (Sept 10, 2013): I believe it would be more correct to say that increasing baseline or endline measurements are ways to decrease the design effect, thereby making the SW design efficient, ...
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2answers
705 views

Linear regression sample size advice

I'm involved in sample size calculation for an oncology clinical trial. Our Primary outcome is quality of life (quantitative, normal). There are two treatment regimes. Therefore I started with a ...
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0answers
136 views

Backing out the standard deviation from information on baseline mean/s.d., and coefficient mean/s.d

I am trying to run a power calculation for a randomized control trial. For this I need a mean and standard deviation for our 'baseline'. There are papers out there which would have a mean and standard ...
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1answer
228 views

Power calculation for cluster-level analysis in cluster randomized trials

I would like to solve for $\pi_1$ in equation 7.14 of Hayes and Moulton's "Cluster Randomized Trials". I can't for the life of me remember how to do so. Here is a link to the equation. Here is the R ...
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1answer
198 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 ...
4
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2answers
227 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 ...
3
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0answers
161 views

Best practice when analysing placebo-controlled within-subject designs (cross-over trial)

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 ...
2
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1answer
164 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 ...
3
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1answer
455 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 ...
4
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1answer
80 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 ...