class: center, middle, inverse, title-slide .title[ # <code>Types of Observational Studies</code> ] .subtitle[ ## Introduction to Categorical Data Anaylsis ] .author[ ### Dr. Zulfiqar Ali (Assistant Professor) ] .institute[ ### College of Statistcal Sciences, University of the Punjab, Lahore ] .date[ ### 21 June 2023 ] --- --- ## Introduction These lecture slides are based on different types of observational studies, including prospective studies, cohort studies, cross-sectional designs, and experimental studies such as clinical trials. These study designs are essential tools in research, allowing us to gain insights into various phenomena, establish causal relationships, and contribute to scientific advancements. Throughout this lecture, we will explore the characteristics, applications, strengths, and limitations of each study type. --- ## Prospective Studies -- - Also known as longitudinal studies or follow-up studies -- - Involve systematic collection of data over a specified period -- - Aim to identify relationships between exposures or risk factors and outcomes -- - Examples: Framingham Heart Study, Nurses' Health Study -- --- ## Cohort Studies -- - A type of prospective study -- - Follow a group of individuals (cohort) over time -- - Assess outcomes based on exposure status -- - Provide insights into natural history, risk factors, and exposure-outcome relationship -- - Examples: Nurses' Health Study, British Doctors' Study --- ## Clinical Trial - Experimental studies to evaluate interventions or treatments -- - Random assignment of participants to experimental and control groups -- - Conducted in phases (I, II, III, IV) to assess safety, efficacy, and long-term effects -- - Provide robust evidence for causal relationships -- - Examples: Vaccine trials, drug trials, behavioral intervention studies --- ## Cross-Sectional Designs -- - Observational studies that gather data on exposure and outcome simultaneously -- - Estimate disease prevalence and identify associated factors -- - Provide a snapshot of population characteristics at a specific time -- - Widely used in public health research and social sciences -- --- ## Observational Studies -- - Aim to observe and analyze relationships between exposures and outcomes -- - Prospective, retrospective, or cross-sectional in nature -- - Valuable for studying rare exposures, natural history, and risk factors -- --- ## Experimental Studies -- - Randomized controlled trials (RCTs) to establish causal relationships -- - Manipulate variables and randomly assign participants to groups -- - Considered the gold standard for evaluating interventions -- - Minimize bias and enable accurate assessment of intervention effects -- --- # References - Agresti, A. (1996). An introduction to categorical data analysis.