Research Methods in Health Psychology Chapter 2

Science Science is not a thing in and of itself. It is a set of methods used to understand natural phenomena with the goals of: –Explanation –Prediction –Control

Assumptions of Science Naturalism –If its real it can be measured Empiricism –Relying on or derived from observation or experiment –Verifiable or provable by means of observation or experiment

Its About the Data Idiographic refers to the individual. Nomothetic - Of or relating to the study or discovery of general scientific laws. When we use nomothetic data we lose specificity to the individual but we gain in that we can now generalize to others.

Levels of Analysis Behavioral/Psychological Organ Systems Molecular Cellular Social/Historical/Environmental

Levels of Rigor of Scientific Data Naturalistic Observation –Case Study Correlation –Most of psychological research –Quasi-experimental Experimental Method –The gold standard

Experimental Method Involves direct controlled manipulation –Independent variable –Dependent variable Two or more groups –experimental group –control group Random assignment

Independent Variable Under control of the experimenter Used to explain changes in the dependent variable Example: Cold virus up the nose –Cold Virus Exposure (Virus, Placebo, Control) –Stress (hi, low, none)

Dependent Variable Not under control by the experimenter Presumed to be caused or affected by the independent variable Example: getting a cold – number of cold symptoms

Random Assignment –Allows us to control for all potential confounds –Each subject has an equal chance of being in each group. –Intact groups not random –Replication to deal with chance variation

Epidemiology

Branch of medicine that investigates the frequency and distribution of disease and related factors.

John Snow The first modern epidemiologist (1854): –Mapping cases of cholera and household use of water sources revealed pattern involving a single water pump Removing the handle from the Broad Street pump ended the epidemic.

Epidemiology - Terms Prevalence-the proportion of the population that has a particular disease at a specific time. Incidence-measures the frequency of new cases of the disease.

Epidemiology - Terms Mortality- Death rate Morbidity-The rate of prevalence/incidence of a disease.

Epidemiology – Ultimate Goals Determine the etiology or origins of a specific disease. To develop and test hypotheses. Discovering who is more likely to have a disease is useful in determining its cause. Discovering risk factors such as dirty water or smoking.

Epidemiology A risk factor is any characteristic or condition that occurs with greater frequency in people with a disease than it does in people free from the disease.

Epidemiology Relative versus absolute risk. Relative: Considered in comparison with something else Relative risk the ratio of incidence or prevalence in the exposed group to that of the unexposed group Absolute risk-The persons chances of developing a disease.

Example: Alameda County Study Started in 1965

Epidemiology - Causation Typically, ER is correlational Certain criteria can be established to assert a causal relationship –Well-designed studies –The direction for the relationship is risk  condition –Dose-response relationship exists between risk factor and condition –A direct, consistent association between an independent variable, such as a behavior, and a dependent variable, such as a disease. –When the risk is removed the probability of disease is reduced –Causality is plausible –Animal studies support a causal link