Measure a continuous outcome y in each subject at the start and end of the study period. For each subject, calculate the change Δ = ystart - yend. Compare the mean value of Δ to 0. This requires the standard deviation S(Δ). The estimate of S(Δ) should be based on data from other subjects who were followed for similar time periods.
Instructions: Enter parameters in the red cells. Answers will appear in blue below.
The standard normal deviate for α = Zα =
The standard normal deviate for β = Zβ =
B = (Zα+Zβ)2 =
C = (E/S(Δ))2 =
AB/C = 0.00
Group size N:
Reference: Rosner B. Fundamentals of Biostatistics. 4th ed. Duxbury Press; 1995. Page 221.