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Computing sample size for a comparison study |
Use the following sample size Webulator to compute sample size for a comparison study.
This Webulator is based on the following sample size formula for a comparison study.
The [Zalpha
] and [Zbeta]
terms are provided in the following tables. The area under the normal curve for the [Zbeta] term is illustrated in the Figure 1.
Conversion table to create the Z beta term |
|
| (one tailed probability estimate=0.05); beta = 0.10 (power = 90%) ; [Zbeta] = 1.64 |
(one tailed probability estimate=0.06); beta = 0.12 (power = 88%) ; [Zbeta] = 1.55 |
| (one tailed probability estimate=0.07); beta = 0.14 (power = 86%) ; [Zbeta] = 1.48 |
(one tailed probability estimate=0.08); beta = 0.16 (power = 84%) ; [Zbeta] = 1.41 |
| (one tailed probability estimate=0.09); beta = 0.18 (power = 82%) ; [Zbeta] = 1.34 |
(one tailed probability estimate=0.10); beta = 0.20 (power = 80%) ; [Zbeta] = 1.28 |
| Conversion table for alpha and percent confidence to Z | |
| (alpha probability estimate of 0.10)=90% [Zalpha] = 1.64 |
(alpha probability estimate of 0.09)=91% [Zalpha] = 1.70 |
| (alpha probability estimate of 0.08)=92% [Zalpha] = 1.75 |
(alpha probability estimate of 0.07)=93% [Zalpha] = 1.81 |
| (alpha probability estimate of 0.06)=94% [Zalpha] = 1.88 |
(alpha probability estimate of 0.05)=95% [Zalpha] = 1.96 |
| (alpha probability estimate of 0.04)=96% [Zalpha] = 2.05 |
(alpha probability estimate of 0.03)=97% [Zalpha] = 2.17 |
| (alpha probability estimate of 0.02)=98% [Zalpha] = 2.33 |
(alpha probability estimate of 0.01)=99% [Zalpha] = 2.58 |
