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Example Using Actual Study Data
Inference for Continuous Data
Particularly suited to clinical development studies, Cytel's CrossOver has procedures to test Carryover Effect, Period Effect and Treatment Effect using either ranks or original data in 2x2 crossover experiments.
Crossover Trial in Patients with COPD (Chronic Obstructive Pulmonary Disease)
Data derived from Byron Jones and Michael Kenward (2003)
- 27 patients allotted to treatment A-B Sequence (A in Period 1 and B in Period 2)
- 29 patients to B-A sequence (B in Period 1 and A in Period 2)
- treatment A represents an active drug and Treatment B a placebo
- the observed response variable is PEFR (Peak Expiratory Flow Rate)
The Relevant Trial Data


Carryover, Period and Treatment Effect Tests (Wilcoxon & Hodges-Lehmann) Performed
Carryover Effect
Period Effect

Treatment Effect

Tests Conclusions
1. There is no significant carryover effect (P=0.2890)
2. The period effect is not significant (P=0.3361)
3. The treatments differ significantly (P=0.002255)
4. The treatment A (active) is significantly better than treatment B (placebo) by a median difference of 11.49 in the value of the response variable PEFR
Reference
Byron Jones & Michael G. Kenward (2003). Design and Analysis of Cross-Over Trials. Chapman & Hall/CRC
Examples - References - More Information
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