Foreground questions can be further classified into four groups: therapy, diagnosis, prognosis, and etiology/harm. Certain study designs are better suited for answering particular question types.
|Question Type||Definition||Appropriate Study Type(s)|
|Therapy||Questions about the effectiveness of treatment to achieve an outcome (drugs, surgical intervention, exercise, counseling, etc.)||Randomized Controlled Trial (RCT)|
|Diagnosis||Questions about identification of a disorder in a patient presenting with specific symptoms||RCT > Cohort Study|
|Prognosis||Questions about the progression of a disease or outcome of a patient with a particular condition||Cohort Study > Case Control Studies > Case Series|
|Etiology/Harm||Questions about the negative impact from an intervention or other procedure||Cohort Study > Case Control Studies > Case Series|