Back Pain Treatment In a study designed to test the effectiveness of paracetamol (or acetaminophen) as a treatment for lower back pain, 1643 patients were randomly assigned to one of three groups: (1) the 547 subjects in the placebo group were given pills containing no medication; (2) 550 subjects were in a group given pills with paracetamol taken at regular intervals; (3) 546 subjects were in a group given pills with paracetamol to be taken when needed for pain relief. (See “Effcacy of Paracetamol for Acute Low-Back Pain,” by Williams, et al., Lancet, doi:10.1016>S0140-6736(14)60805-9.) Is this study an experiment or an observational study? Explain.

The number of subjects used to test the effectiveness of paracetamol on lower back pain relief is 1643.

The patients were divided into three groups in a random manner.

1) Treatment 1(Placebo group): Conducted on 547 subjects

2) Treatment 2(Pills intake at regular time gaps): Conducted on 550 subjects

3) Treatment 3 (Pills were taken only when needed): Conducted on 546 subjects

Experiment and observational study are two types of methods to conduct a statistical study. An experiment records measurements by applying the treatment on experimental units, while an observational study records the measurement of the response variable without applying any modification to the experimental unit.

In the study, the experimental units are 1643 patients who suffer lower back pain. The patients are divided into three treatment groups, which signify that responses are taken after applying one of the three types of treatment.

Thus, the study is an experiment.