Chapter 6

lesting o honge t0,l5illIiir Current Procedurea New Procedure| 2 3 4 5 6 7 A 910 11 12 13 14 15PatientFlgure 5.5. Doto blleaed on Rehohilitation line.18The mulchcwer bedsresuhed inoys to pur:h suppliedmulcn on ord ofier thekept by theimproved:1 that anyIted in ther was onlyof applica-: less. Thech was anrrovide thered duringing appearch?"and a:rgure't.'rr.y after theIIiISi n ult a n eo u s bn p orim nsIn a simultaneous comparison test (commonly called a paired comparisonstudy), two or more alternatives are compared at the same time, in the samespace, or under other similar conditions. When one of the alternatives is thecurrent system, the test is often called a simultaneous comparison with acontrol. By comparing alternatives in such a way, the effect of external events onthe different allernatives can be studied during the test. A simultaneouscomparison test can therefore help to rule out alternate explanations for thermprovement.Figure 6.5 shows the data a physician, Dr. Smith, collected on rehabilitationtime. The data were collected during a simultaneous comparison test of a newrehabilitation procedure. Based on previous research, Dr. Smith's degree of beliefwas high that the new procedure would result in improvement. It was also herbelief that if it turned out that the new procedure was not an improvement, therisks involved were not high. She advised the patients and received their consentto include them in the test of the new procedure.The run chartjuxtaposes the data that resulted when the current rehabilitationmethod was used on a group of patiens with the data obtalned from patientsusing the new method. Both sets of data were collected over the same four-monthperiod. The run chart reveals the impact of the change and the effect of an externalevent on both the currenl and the new method. The external event thatcaused a higher rehabilitati.on time for both procedures (although the new procedurewas still lower) was identified as the presence of a new physical therapist.This therapist conducted the rehabilitation for a short time when the regulartherapist was on vacation. The results of this test increased Dr. Smith's degree ofbelief that the new method was an imDrovement over the old.