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Table 3 Assumptions and detectable effect sizes informing sample size for the project

From: Optimizing treatment protocols for spinal manipulative therapy: study protocol for a randomized trial

 

Assumptions for outcome measures

Stiffness (N)

Multifidus activation (mm)

Oswestry

Numeric Pain Rating

Assumption

 Mean (SD)

5.55 (1.60)

2.60 (0.124)

24.3 (14.9)

5.06 (2.12)

 Pre-post score correlation

0.80

0.70

0.70

0.45

 MCID or hypothesized effect size from prior work

0.40

0.074

6.0

2.0

Type of effect

Detectable effect size

 Main effect

0.37

0.034

4.12

0.76

 Pairwise interaction

0.74

0.068

8.24

1.53

 Conditional comparison

0.53

0.048

5.83

1.08

 Main effect in 50% of participants

0.53

0.045

5.83

1.08

 Interaction in 50% of participants

1.05

0.091

11.65

2.16