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Table 2 Power calculations for continuous outcome measures

From: TAILOR – tapered discontinuation versus maintenance therapy of antipsychotic medication in patients with newly diagnosed schizophrenia or persistent delusional disorder in remission of psychotic symptoms: study protocol for a randomized clinical trial

Outcome Lowest clinically relevant difference Expected standard deviation Calculated power Reference
Antipsychotic haloperidol equivalents 1.5 3 98% Own unpublished data
Negative symptoms (negative dimension, based on mean of four global SANS scores) 0.4 1.2 75% Petersen [45]
Cognition, overall score (BACS total) 15 42 80% Melau [46]
Client satisfaction (CSQ) 2 5 88% Petersen [45]
Social function (GSDS) 1.6 4.5 80% Standard deviation based on [22]. Lowest clinically relevant difference is not known, but is set to Cohen’s d = 0.356, i.e.,low-to-moderate effect size
  1. CSQ Patient Satisfaction Questionnaire, BACS Brief Assessment of Cognition in Schizophrenia, GSDS, Groningen Social Disabilities Schedule, SANS Schedule for Assessment of Negative Symptoms