Role of Research Question Organizing principle for the entire study Target population Sample Data collection method Measures Analysis Forum for reporting the results

Types of Research Questions Like research goals Descriptive Association Causal

Descriptive How often…. How much… What number….. What percentage….. Was there a change… Has the incidence increased… Who is affected… When did it start… Where is it concentrated…

Descriptive: Childhood Type 2 Diabetes Has the incidence increased? Increased from 0.7 per 100,000 in 1982 to 7.2 per 100,000 in 1994 in Cincinnati, OH (Pinhas-Hamiel et al., 1996). Who is affected? Pima Indians in Arizona have an unusually high prevalence of Type 2 diabetes in childhood (Dabelea et al., 1998).

Association/Causal Association – risk factors Causal – direct causes Collectively known as determinants

Example: Obesity as a Cause or Risk Factor Are obese individuals more likely than those who are not obese to have cardiovascular disease (CVD)? Study of firefighters showed that extremely obese subjects had an average of 2.1 risk factors for CVD compared to 1.5 for normal weight firefighters (Soteriades et al., 2005). Is obesity associated with colorectal cancer? Subjects with colorectal cancer had higher body mass indices (BMI) compared to those without cancer (Campbell et al., 2010).

Causal/Evaluation Evidence-based programs If X causes or increases the risk for Y, then decreasing X should decrease Y. Decreasing or preventing X is a deterrent for Y. Types of questions: Does Program Alpha have a desirable effect on X? Is Program Alpha effective in preventing Y?

Example: Effect of Modest Weight Loss on Preventing Type 2 Diabetes DPP -- Experimental Study of those at high risk for diabetes Diet and exercise Medication Usual care Outcome – Reduced incidence of diabetes

Sources for Research Questions Everyday life Practical Issues in the field of study Relevant research studies Theory

Questions from Everyday Life Why do my daughter and her soccer teammates get so many concussions? How many children at my kids school are taking medication for ADHD?

Questions from Issues in the Field of Study Major questions that plague the field of public health. What are the causes of the increasing prevalence of obesity in the U.S.? Diabetes in the U.S.? What is an effective vaccine for HIV? What is an effective cure for infection with hepatitis C virus?

Relevant Research Studies Results of studies on the topic of interest can guide the more specific focus of research questions and hypotheses. Replicate the results to provide more support. Test in different type of population. Measure exposure and outcome using different techniques – self report, biomarker, physical measurement Example Are residents of food desert areas (i.e., neighborhoods with no access to fresh produce) more likely than others to be obese?

Good Research Questions Identify Characteristics of the target population (e.g., gender, age, health problem, place of residence) Study measures (e.g., exposure, outcome, risk factors) Type of research goal (e.g., descriptive, association, causal, evaluation) Does the frequency of receptive syringe sharing predict the incidence of hepatitis C seroconversion?

Key Components -- Study Feasible – it must be possible to answer the question analytically (scientifically, time, resources) Interesting – the question should generate interest among the consumers of the research Novel – the question should add something new to the field of research Ethical – procedures needed to answer the question must not compromise the protection of human subjects Relevant – the question should address issues that are timely, have an impact on the study population, and make a contribution to the field of study

For This Class No Randomized Clinical Trials No Secondary Data Analysis