- Does garlic reduce serum cholesterol levels?
- Is montelukast (Singulair®) as effective as an inhaled steroid in treating asthma?
- Is induced abortion a risk factor for breast cancer?
If the question is too broad, it may not be useful when applied to a particular patient. For example, whether chemotherapy is effective in cancer is too broad a question (the number of studies addressing this question could exceed 10,000).
If the question is too narrow, there may not be enough evidence to answer the question. For example, the following question is too narrow: Is a particular asthma therapy effective in Caucasian females over the age of 65 years in Central Pennsylvania?