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Table 1 Sample size calculation

From: The effectiveness and cost-effectiveness of telephone triage of patients requesting same day consultations in general practice: study protocol for a cluster randomised controlled trial comparing nurse-led and GP-led management systems (ESTEEM)

Number per group* ICC Design factor Number of patients per group Final number of patients per group+ Number of practices per group
 305* 0.01 3.26 994 1,867 4
 305* 0.05 12.3 3,751 7,046 14
 228^ 0.01 3.26 743 1,396 3
 228^ 0.05 12.3 2,804 5,267 10
  1. *At 90% power and 5% alpha; ^80% power and 5% alpha (both using the above means and SDs as per text); +after 6%[3, 27, 28] of patients being excluded, 10%[14, 28, 29] initially declining participation, 30%[2729] non-response to the request to return written consent to note review; of responders, 10% decline note review.