Week 3

A study that is done where a particular trend or concept is observved

Experimental studies are ones where researchers introduce an intervention and study the effects.

Descriptive Relational Causal

• Background info (Lowest, weakest, worst) • Case - controlled studies / Reports • Cohort studies • Randomised controlled trials (RCTs) • Critically - appraised individual articles • Critically - appraised topics • Systematic reviews

collect data from many different individuals at a single point in time

Advantages - More time - efficent - Often less expensive - Reduced likelihood of attrition Disadvantages - Less powerful (within group variance is higher) - 'Cohort problem". E.g. assessing physical activity participation but neglecting to recognise that school PE changes over the years

A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition

A study design where one or more samples (called cohorts) are observed over a period of time. The incidence of disease in the exposed group is compared with the incidence of disease in the unexposed group.

Advantages - Potentially very rich data set - Same people are measured, so minimises the effect of other variables Disadvantages - Drop out, mortality - Non - equivalence of those who dropped out and those who remained in the study. E.g. may no longer representative of the target population - Familiarity with the experiment. E.g. responses over time may be influenced by previous tests

Cohort case studies cross-sectional case-control

Single group interventions Quasi - experimental Randomised controlled trials

• Take a group of people, intervene Measurements at baseline and follow - up (s)

• Measures are completed in an intervention and comparison group with similar characteristics • Group are not randomised

Advantages - Useful when randomisation is difficult - Can save time and resources - Maybe a reasonable alternative to RCT Disadvantages - Groups may differ, introducing bias - Need to document characteristics - Need to acknowledge potential bias - Weakens potentional casual effects

• Controlled • Random allocation to groups Pre and post measures

A systematic review is a review of a clearly formulated question that uses systematic and reproducible methods to identify, select and critically appraise all relevant research

• Present the evidence base in an accessible format. Helping readers find the results of research quickly and to assess the validity, applicability and implications of those results • Provide more reliable findings from which conclusions can be drawn and decisions made • The needs of healthcare providers, consumers, researchers, and policy makers