Question

ch 18* a writer in a medical journal says: “an uncontrolled experiment in 37 women found a significantly improved mean clinical symptom score after treatment. methodologic flaws make it difficult to interpret the results of this study.” the writer is skeptical about the significant improvement because

the response variable might not have an exactly normal distribution in the population.
the p - value given was p = 0.048, which is too large to be convincing.
there is no control group, so the improvement might be due to the placebo effect or to the fact that many medical conditions improve over time.

Explanation:

In an experiment, a control group is crucial. Without it, it's hard to determine if the improvement is due to the treatment itself. It could be the placebo effect (where participants think they're getting treatment and feel better) or natural improvement over time. A normal distribution of the response variable isn't the main issue here as the problem mentions "methodologic flaws" related to the experiment design (an uncontrolled experiment). Also, a \( P - value\) of \(0.048\) is less than the common significance level of \(0.05\) (if we assume a two - tailed test at the \(5\%\) significance level), so it's not the reason for skepticism.

Answer:

there is no control group, so the improvement might be due to the placebo effect or to the fact that many medical conditions improve over time.