Exploring quantitative data Flashcards
What is the research process?
A process that uses the scientific method to establish, confirm and/or reaffirm certain pieces of knowledge supported by strong evidence
Why do we use the research process?
- Create theories
- Find solutions to problems
- Find problems to solutions
- Find some sort of truth
What does the research design encompass?
Plan of sampling, data collection, measurement and analysis
Methodology
Study design
Data analysis
Types of study designs in medicine
- Basic studies
- Observational studies
- Experimental (interventional) studies
- Economic evaluations
- Meta-analysis/systematic review
What is an observational study?
- Non-interventional
- variables are not manipulated by researchers
- Researchers observe natural relationships between factors and outcomes
Types of observational studies
- Cross-sectional studies
- Longitudinal studies
- Case-control studies
- Cohort studies
- Survey studies
What is a Cross-sectional study?
A study that assesses a population, as represented by the study sample, as a single point in time
–> they reflect the situation of a disease or clinical outcome at a particular moment in a particular population
Cross-sectional study example
- Enrolling current smokers or never smokers and assessing whether or not they have decreased lung function
How is a cross-sectional study conducted?
- Participants recruited based on inclusion and exclusion criteria
- Study the exposure and outcome at the same time
- Estimate the prevalence (of outcome and exposure as well) –> calculate odds ratio
What is a longitudinal study?
They use continuous or repeated measures to follow a particular individual over prolonged periods of time (year or decades)
- -> observational in nature
- -> collects quantitative and qualitative data without external influence being applied
Longitudinal study example
The longitudinal study of the Office of Population Censuses and Surveys
What is a case-control study?
Researchers identify study participants based on their case status (i.e. diseased or not diseased)
–> Quantification of the number of individuals among the cases and the controls who are exposed allows for statistical associations between exposure and outcomes to be established
Case-control study example
Analysing the relationship between obesity and knee replacement surgery
–> Cases are participants who have had knee surgery, and controls are a random sampling of those who have not, and the comparison is the relative odds of being obese if you have knee surgery as compared to those that do not
What are cohort studies?
involve identifying study participants based on their exposure status and following them through time to identify which participants develop the outcome(s) of interest
Cohort study example
cohort of 5766 men aged 35–64 at the time of examination who were recruited from workplaces in the west of Scotland between 1970 and 1973. The study investigated the association between socioeconomic position in early life (when the participants were children) and cause specific mortality. Relative rates of mortality adjusted for age for men with fathers in manual versus non-manual occupations were 1.52 (95% confidence interval 1.24 to 1.87) for coronary heart disease, 1.83 (1.13 to 2.94) for stroke, 1.65 (1.12 to 2.43) for lung cancer, 2.06 (0.93 to 4.57) for stomach cancer, and 2.01 (1.17 to 3.48) for respiratory disease.
What are survey studies?
Research based off of surveys
Benefit of surveys
enables the researcher to describe the characteristics of the sample being studied and to make generalisations to the larger population of interest. Surveys are particularly useful for collecting information about research phenomena that are not directly observable or measurable. They are also useful for collecting data from people who are widely distributed geographically, since direct contact between researcher and research participant is not necessary.
Types of surveys
- Epidemiological
- Surveys on attitudes to a health service intervention
- Questionnaires assessing knowledge on a particular topic or issue
What are interventional studies?
those where the researcher intervenes or manipulate the variable (s) at some point throughout the study.
Types of interventional studies
- RCT
- Pre-post studies
- Non-randomised controlled trials
What is an RCT?
a trial in which subjects are randomly assigned to one of two (or more) groups: one (the experimental group) receiving the intervention that is being tested, and the other (the comparison group or control) receiving an alternative (conventional) treatment.
Features of an RCT
- The sample to be studied will be appropriate to the hypothesis being tested so that any results are appropriately generalisable. The study will recruit sufficient patients to allow it to have a high probability of detecting a clinically important difference between treatments
- There will be effective (concealed) randomisation to eliminate bias
- Both groups will be treated identically in all respects except for the intervention being tested and to this end, patients and investigators will ideally by blinded to which group an individual is assigned
- The investigator assessing outcome will be blinded to treatment allocation
- Patients are analyzed within the group to which they were allocated, irrespective of whether they experience the intended intervention (intention to treat analysis)
- The analysis focuses on testing the research question that initially led to the trial
What are pre-post studies?
A pre-post study measures the occurrence of an outcome before and again after a particular intervention is implemented.
Example of pre-post study
comparing deaths from motor vehicle crashes before and after the enforcement of a seat-belt law.
What are the non-randomised trials?
interventional study designs that compare a group where intervention was performed with a group where there was no intervention –> suggest possible relationships between the intervention and the outcome.
