A randomized research study is designed to determine whether albuterol by nebulization improves pulmonary function in children with bronchiolitis.

Question

A randomized research study is designed to determine whether albuterol by nebulization improves pulmonary function in children with bronchiolitis. Twenty chidren, ten of whom receive albuterol and ten of whom receive a placebo, are recruited into this double-blind, placebo-controlled study. A 15% improvement in forced expiratory volume in one-half second (FEV 0.5) after treatment is considered to be a clinically significantly improvement. Analysis of the FEV 0.5 values by unpaired t-test yields a p value of 0.15. A conclusion that albuterol does not improve FEV0.5 in infants with bronchiolitis may most justifiably be criticized because of whoch of the following? A. The findings of the insignificance are a valid result (incorrect) B. The p value was <0.05 C A paired t-test should have been employed D. A t test is invalid in this context E. Statistical power has not been considered

Answer 1

The conclusion that albuterol does not improve FEV0.5 in infants with bronchiolitis, based on the given p value of 0.15, may be most justifiably criticized because of option E: "Statistical power has not been considered."

Here's why each choice is evaluated as follows:

1. A. The findings of the insignificance are a valid result (incorrect): This option is incorrect because the p value of 0.15 indicates that the results are not statistically significant according to the conventional threshold of 0.05. However, this does not automatically validate the conclusion that there is no effect; it may reflect a lack of power in the study to detect a true effect.
2. B. The p value was <0.05: This is incorrect because the p value given is 0.15, which is greater than the conventional threshold of 0.05 for statistical significance.
3. C. A paired t-test should have been employed: This is not necessarily correct. A paired t-test is used when the measurements are taken on the same subjects before and after a treatment. In this study, the design is a between-subjects design (different children in the treatment and placebo groups), making the unpaired t-test appropriate.
4. D. A t test is invalid in this context: There is no indication that a t-test is invalid in this context. The t-test is a common statistical method used to compare the means of two groups, which seems appropriate for this study design.
5. E. Statistical power has not been considered: This is the most justified criticism. Statistical power refers to the likelihood that a study will detect an effect when there is an effect to be detected. A study with low power may fail to detect a true effect, leading to a false conclusion of no difference. Given the small sample size (20 children) and a p value of 0.15, it is quite possible that this study was underpowered. Without considering power, the conclusion that albuterol does not improve FEV0.5 might be premature.

Therefore, the most valid criticism of the conclusion is that it does not take into account the potential lack of statistical power of the study.