Patients in an outpatient treatment center receiving daily ...

[jace]

Patients in an outpatient treatment center receiving daily dressing changes were studied by means of a quasi-experimental design using a crossover strategy.
 
  Patients were administered either Morphine Contin or Percocet, by random assignment, on one day, and the other medication on the following day. Pain scores were obtained for both days, recorded and analyzed. Why was a crossover strategy used? (Select all that apply.)
  a. Because dressing changes may become less painful in some patients over time, as wounds heal, this strategy balanced the pain scores, across participants.
  b. Because dressing changes may become more painful over time, as debridement occurs, exposing raw tissue, this strategy balanced the pain scores, across participants.
  c. Because patients were not consented for the study and had to receive at least one traditional treatment.
  d. Because dressing changes may become less painful over time, as patients know what to expect, this strategy compensated by alternating first-treatment across patients.

Question 2

What is the disadvantage of using an event partitioning design? (Select all that apply.)
 
  a. It avoids complicated statistical analyses.
  b. The validity of its results depends on the assumption the all persons in the study are similar.
  c. It does not require as much time for data collection as does a longitudinal study.
  d. It measures small increments of an intervention instead of the whole intervention.
  e. It makes the assumption that a key event continues to occur in the same way.

[CourtneyCNorton]

Answer to Question 1

ANS: A, B, D
Crossover, or counterbalancing, is a strategy designed to guard against possible erroneous conclusions resulting from carryover effects. With counterbalancing, subjects are randomly assigned to a specific sequencing of treatment conditions. This approach distributes the carryover effects equally throughout all the conditions of the study, thus canceling them out. The carryover effect, in this case, was pain related to healing and pain expectation.

Answer to Question 2

ANS: C, E
A merger of the cross-sectional or longitudinal and trend designs, the event-partitioning design, is used in some cases to increase sample size and to avoid the effects of history on the validity of findings. Cook and Campbell referred to these as cohort designs with treatment partitioning. The term treatment is used loosely here to mean a key event that is thought to lead to change. In a descriptive study, the researcher would not cause or manipulate the key event but rather would clearly define it so that when it occurred naturally, it would be recognized. Data across subjects is assumed to be comparable, and a larger sample size would be available for later studies of changes over time.

[jace]

TYSM

[dantucker]

Excellent