Research question/HypothesisEvery research work must have research question (s)/hypothesis.

Research question:A Research Question is a statement that identifies the phenomenon to be studiedMany studies have more than one research question.

FINER Criteria for a Good RQFeasibleAdequate number of subjectsAdequate technical expertiseAffordable in time and moneyManageable in scopeInterestingGetting the answer intrigues the investigator and her/his friendsNovelConfirms, refutes or extends previous findingsProvides new findingsEthicalAmenable to a study that institutional review board will approveRelevantTo scientific knowledgeTo clinical and health policyTo future research

Example of research question For cross sectional descriptive studies:What is the prevalence of dry eye among the computer users of Dhaka university?Who are the people mostly affected by conjunctivitis?For case control studies:Is there any association between computer use and dry eye? What are the risks of conjunctivitis?

For interventional study:Does amitryptyline reduce frequency of migraine attack compared with propranolol?

Components of the clinical question

Population - type of person /patientIntervention (exposure) - type of exposure Comparisons - type of control Outcomes - type of outcome

Refining the clinical question

Type of exposure Are anticoagulant agents useful in patients who have had a stroke? Type of patient

The well-formulated question

Type of exposure Type of outcomes Do anticoagulant agents improve outcomes in Type of person patients with acute ischemic stroke Type of control compared with no treatment?

HypothesisDefinition:A hypothesis is an educated guess about how things work.Many study questions undergo a further transformation into a final and most specific version, termed research hypothesisWhen Hypothesis?Other than descriptive type of cross sectional study all may have a hypothesisCharacteristics of a good hypothesis:SimpleSpecificStated in advance

When hypothesis should be formulated? If any of the following terms appear in the research question:Greater thanLess thanCausesLeads to Compared withMore likely thanAssociated withRelated to Similar to Correlated with

Example:Chocolate may causes migraineBacterial growth may be affected by temperature Ultra violet light may cause cataract

Simple versus complexSimple hypothesis:One predictor and one outcomeE.g. A sedentary lifestyle is associated with an increased risk of proteinurea in patients with diabetesComplex hypothesis:More than one predictor (a sedentary lifestyle and alcohol consumption are associated with an increased risk of proteinuria in patients with diabetes) or More than one outcome (alcohol consumption is associated with an increased risk of proteinuria and neuropathy in patients with diabetes)

Types:Null hypothesis or hypothesis of no difference:There is no association between the predictor and outcome (e.g. there is no difference in the frequency of dinking well water between subjects who develop peptic ulcer disease and those who do not)Alternative hypothesis: The proposition that there is an association (e.g. the frequency of drinking well water is different in subjects who develop peptic ulcer than in those who do not)In research only alternative hypothesis should be written. The null hypothesis does not need to be written in the dissertation/thesis.

One-and two-sided alternative hypothesisOne sided: specifies the direction of association between predictor and outcomeE.g. drinking well water is more common among subjects who develop peptic ulcersTwo-sided: specifies association; does not specify directionE.g. Subjects who develop peptic ulcer disease have a different frequency of drinking well water than those who do not.