RESEARCH SUPPORT
Pilot and Feasibility Trial Analysis
Estimating Feasibility, Not Efficacy
Pilot trial statistical analysis that estimates recruitment, retention and adherence with intervals, reads progression criteria against what was prespecified and shows any treatment effect only as a planning input.
No Commitment Required
Strictly Confidential
In-House PhD-Level Statisticians
Fixed Project Fee
Same-Day Response
What Does a Pilot Trial Analysis Cover?
Pilot trial statistical analysis asks whether a larger trial can be run, which is a different question from whether the intervention works. It estimates recruitment, retention and adherence with confidence intervals and sets them against thresholds fixed in advance. Feasibility trial outcomes are therefore rates of the trial process, and pilot study progression criteria are judged on those rates, while the treatment effect is shown with its wide uncertainty and used only to inform the plan for a definitive trial. OnlineSPSS, a specialist statistical consultancy for academic, clinical and professional research, keeps pilot analyses in-house, where PhD-level statisticians log every decision. Whether to proceed to the main trial stays with the trial team.
WHEN TO ENGAGE
Pilot Milestones That Need a Statistician
The analysis a pilot needs depends on how much of it has been settled, and the thresholds that govern the decision are easiest to set before enrollment starts.
Thresholds Not Yet Fixed The pilot is designed, but the recruitment, retention and adherence levels that decide whether to proceed have not been set, so they are fixed in the protocol before the first participant enrolls.
Enrollment Under Way Participants are being recruited, and the team wants monitoring counts with intervals so that a shortfall in a single site or arm is seen while the design can still be adjusted.
Follow-Up Complete Data collection has ended and the process outcomes, the descriptive results and the planning inputs for the main trial now have to be produced from the records in a defensible form.
Funder or Ethics Query A funder, a committee or a reviewer has asked what the pilot showed and how the main trial was sized, and the answer needs rates, intervals and the stated limits of a small study.
PILOT ANALYSIS SCOPE
Process Outcomes and Planning Inputs
A pilot is analyzed only for what it can show: whether the trial is feasible and what the next one should assume.
Process Outcomes
Consent, recruitment, retention and adherence are estimated as proportions or rates with 95% confidence intervals, and the denominator behind each one is stated.
Progression Criteria
Thresholds are fixed beforehand, and results are read against them, often as stop, amend or go zones, so the decision does not depend on how the data turned out.
Pilot Sample Size
The size of the pilot is justified by how precisely a rate or a standard deviation will be estimated, not by power to detect a treatment effect.
Cautious Effect Estimates
Outcome differences are shown descriptively with intervals, without a significance verdict, and for time-to-event outcomes Clinical, Survival & Epidemiological methods apply.
Inputs for the Main Trial
The outcome variance and, in cluster designs, the intracluster correlation are reported with their uncertainty, a step shared with Research Planning & Study Design.
Reporting the Pilot
Reporting follows the CONSORT extension for pilot and feasibility trials, and design questions for the definitive trial draw on Clinical Trials.
PILOT TRIAL PITFALLS
Reading a Pilot Beyond What It Can Show
Most pilot weaknesses come from asking a small trial a question it was never sized to answer, or from setting the criteria after the results were visible.
Efficacy Tested in a Pilot A significance test on the treatment effect is run in a trial too small to detect a plausible effect, so a null result is read as no effect and a positive one is overstated.
Pilot Effect Used as the Target The effect seen in a small pilot is entered directly as the target of the main trial, though it is estimated imprecisely, and a more cautious value is usually considered.
Criteria Set After the Data Thresholds chosen once retention is known can be fitted to the result, so a go decision looks planned when it was not, and the protocol should hold them from the start.
Rates Without Intervals A retention rate is quoted as a single percentage, although in a small pilot its interval is wide and may span the progression threshold, which changes what can be concluded.
Dropout Counted, Not Examined Withdrawals are tallied without their reasons, arm or timing, though a difference in dropout between arms can point to an acceptability problem with one condition.
Clustering Overlooked In a cluster pilot with few clusters, the intracluster correlation is very uncertain, so a planning value taken from one pilot is labeled as such and not treated as settled.
DELIVERABLES
Outputs That Inform the Next Trial
The outputs are arranged around the decision to proceed and the questions a funder is likely to raise about the pilot.
Progression Table Every prespecified criterion with its observed rate, 95% confidence interval and the decision zone it falls into, stated without softening.
Enrollment Flow Diagram Screening, eligibility, consent, allocation and follow-up counts in a flow diagram, so that losses at each stage can be seen and discussed.
Retention and Adherence Summary Retention and adherence by arm and by time point, with intervals and the recorded reasons for withdrawal summarized in a short table.
Descriptive Outcome Tables Outcome summaries by arm with intervals and standard deviations, and no conclusions drawn from p-values alone, since the pilot was not designed to test efficacy.
Planning Memo Variance estimates and a range of plausible targets for the definitive trial, each with the uncertainty around it, for the sample size discussion.
Funder Feasibility Statement A concise statement of what the pilot established, in the conventions of Medical, Health & Clinical Research, for an application or committee.
ILLUSTRATIVE EXAMPLE
A Pilot Judged on Feasibility Alone
An illustration of how a small randomized pilot is analyzed for progression, with its outcome differences kept descriptive.
ILLUSTRATIVE EXAMPLE · SPEECH-LANGUAGE THERAPY PILOT RESEARCH · UNITED STATES
A speech-language pathology researcher at a university clinic piloted a home practice program for adults after stroke, randomized to the program or usual therapy, ahead of an application for a definitive trial.
The protocol had already named three progression criteria: monthly recruitment, completion of the home practice logs and retention at the final visit, each with a stop, amend or go rule. The analysis estimated each as a rate with an exact confidence interval. The complication was that recruitment met its threshold while log completion was uneven in the program arm and the retention interval spanned the lower threshold, so the result fell in the amend zone rather than the go zone. The outcome measure was summarized by arm with intervals only, and its standard deviation was reported with the uncertainty that a small sample leaves.
Outcome: The researcher received the progression table with the observed rates and their 95% confidence intervals, the flow diagram, the descriptive outcome tables, a planning memo and statistical wording for the methods, matched to the output, for the researcher to check and incorporate.
This example does not describe a real client or project. We never share details of actual client work, in line with the confidentiality we promise every researcher. This illustrative example is included to show the type, scope, and standard of work involved in this kind of analysis.
SOFTWARE
Recomputing Rates as Enrollment Grows
The process outcomes are simple in form but are recalculated as enrollment grows, so the choice favors a program in which the tables can be regenerated.
HOW WE ASSESS YOUR PROJECT
We Review Your Actual Research
Your assessment is based on a review of your actual research materials and analytical requirements, not a generic project category.
You Submit Your Project Details
Share whatever is available at the current stage, such as the research aim, protocol or proposal, dataset, variable list, manuscript or statistical requirements.
We Review Your Research and Define the Scope
Your statistically trained Research Coordinator reviews the materials to understand the study design, research questions, data structure, analytical requirements and expected deliverables. If clarification is needed, additional documents or information can be requested before the assessment is finalized.
Your Analysis Is Completed and Delivered
Once the scope and fixed project fee are agreed, the in-house statistician completes the work and the Research Coordinator remains the communication point through delivery, with the analysis, deliverables and timeline as agreed.
RESEARCH RESPONSIBILITY
The Decision to Proceed Is the Team's
The pilot analysis informs whether a definitive trial goes ahead, and that judgment, with the trial it concerns, belongs to the investigators.
Agreed Statistical Support OnlineSPSS provides the agreed methodological, analytical and statistical reporting support, defined in a scope that is confirmed before any work begins.
No Intellectual Contribution OnlineSPSS does not claim any intellectual contribution to your research. Authorship of the report, thesis or article remains yours.
Your Research Decisions The trial design, the progression thresholds, the decision to proceed, the interpretation of the findings and the conclusions remain yours, with overall responsibility.
Confidential Handling Research data and project details are handled confidentially, project information is not published, and an NDA is available where required.
FREQUENTLY ASKED QUESTIONS
Pilot Trial Analysis: Thresholds, Effects and Size
Feasibility decisions rarely fall cleanly into go or stop, and what happens to the pilot's own data and to its thresholds shapes how those decisions are read.
What does pilot trial statistical analysis cover?
Pilot trial statistical analysis at OnlineSPSS covers the estimation of recruitment, retention and adherence with confidence intervals, the reading of those rates against prespecified progression criteria, and the planning inputs for a definitive trial. Randomized and single-arm pilots are both handled, whether the trial tests a drug, a device or a behavioral program.
What happens when a criterion falls in the amend zone?
The trial is usually judged feasible with changes. The analysis shows which part of the process fell short, by arm, site or month, and how wide the interval around it is, so the team can judge whether a change to recruitment, procedures or the intervention is likely to correct it. The decision and the change remain with the investigators.
Should data from the pilot be combined with the main trial?
Usually not, when the pilot led to changes in the protocol, the procedures or the outcome measure, because the two samples then answer slightly different questions. An internal pilot, planned in the protocol as the first stage of the main trial, is the exception: its participants are counted in the final analysis as the protocol sets out.
Who sets the progression criteria, and when?
The investigators set them, ideally in the protocol before enrollment, with the statistician advising on what the pilot’s size can estimate. Criteria chosen once the results are known lose their value as a decision rule, so the date they were fixed is recorded alongside the thresholds.
How do you protect my research data and confidentiality?
Your data and project details are handled confidentially, and project information is not published. Researcher names and institutions are not used publicly without permission. An NDA is available where required and can be arranged before sensitive materials are shared. Read more about confidentiality and data security.
What happens when I request an assessment, and how long does it take?
You share your research question, design and relevant materials, such as the protocol, the progression criteria and the recruitment log, and a statistically trained Research Coordinator reviews the request and responds the same day. The analysis, deliverables, timeline and one fixed project fee are then confirmed before any work begins, so the timeline follows from the agreed scope.
Still have a question? Find more answers in our full FAQ.
NEXT STEP
Agree the Stop and
Go Rules First
A pilot protocol or a draft statistical plan shows which thresholds are already fixed and which still need a decision before the first participant is enrolled.
No Commitment Required
Strictly Confidential
Fixed Project Fee
In-House PhD-Level Statisticians
Same-Day Response
Serving Researchers Since 2014