Table 2 CTU statistician roles and models of working

Overview of statistician roles

Role name

Description

Trial statistician

Typically responsible for day-to-day statistical input into the design, conduct and reporting of the trial. Roles include (but are not limited to):

• Input into database and CRF design

• Producing regular monitoring reports and liaising with trial committees (e.g. TMGs, DMCs and TSC)

• Planning and conducting the interim (if applicable) and final statistical analysis

Lead statistician^a

Leads on and has overall responsibility for statistical aspects of the trial. Responsible for oversight of the TS including advice and quality control. Often a co-applicant involved in the grant funding application

Non-blinded Statistician

A statistician (not the trial or lead) statistician that is able to access data by allocation. The main purpose of an unblinded statistician is to enable trial and lead statisticians to remain blinded where possible

Statistical models

Role name

Blinding

Meeting attendance^c

TMG

DMC (o)

DMC (c)

TSC

Model 1—Trial statistician can be unblinded^b to maintain blind of lead statistician

Trial statistician

Blinded at outset but can be unblinded to preserve blinding of lead statistician

Lead statistician

Remains blinded until database lock

Model 2—TS remains blinded, lead statistician (LS) can be unblinded^b

Trial statistician

Remains blinded until database lock.

Lead statistician

May become unblinded (if required) to maintain the TS blind. If not previously unblinded, they are unblinded at database lock

Model 3—TS and LS remain blinded by having a third unblinded statistician

Trial statistician

Remains blinded until database lock

Lead statistician

Remains blinded until database lock

Non-blinded Statistician

Unblinded

Model 4—TS and LS remain ‘pseudo-blinded’ by using coded groups^d

Trial statistician

Remains “blinded” to true treatment allocations until database lock

Lead statistician

Remains “blinded” to true treatment allocations until database lock

Model 5—Both statisticians can be unblinded^b during the trial

Trial statistician

May become unblinded if required. If not during the trial, they are unblinded at database lock

Lead statistician

May become unblinded if required. If not during the trial, they are unblinded at database lock

Model 6—All statisticians are unblinded^b

Trial statistician

Unblinded

Lead statistician

Unblinded