Health Psychology An Introduction to Behavior and Health 8th Edition By Linda Brannon – Test Bank
Conducting Health Research
- The Placebo in Treatment and Research
A placebo is an inactive substance or condition that can cause people to improve or change their behavior. Both expectancy and learning contribute to this effect.
- Treatment and the Placebo
The placebo effect is an advantage for treatment, boosting its effectiveness. This effect may be responsible for about 35% of improvements, but some treatments (such as antidepressant drugs) have higher placebo effects than others (such as treatment for broken bones). Placebos can also produce negative effects, called the nocebo effect. Both placebo and nocebo effects are real and produce symptoms and relief that are indistinguishable from the effects obtained from drug and other physical treatments.
- Research and the Placebo
The placebo effect presents problems for research because they prevent a clear interpretation of treatment effectiveness. Researchers try to control for placebo effects by designing single-blind and double-blind designs, arranging for participants and even researchers to be unaware of which participants receive a placebo and which get active treatment.
- Research Methods in Psychology
For research to contribute to knowledge about health, scientists should be familiar with one another’s work, use controlled methods, try to keep personal biases from contaminating results, make claims cautiously, and replicate their studies. To understand behaviors related to health and disease, researchers use a variety of methods, including correlational studies, cross-sectional and longitudinal studies, experimental designs, and ex post facto designs.
- Correlational Studies
Correlational studies indicate the degree of relationship between two variables, such as the number of stressful life events and the risk of heart attack. This approach is one type of descriptive research. In correlational studies, the relationship between two variables is expressed in terms of correlation coefficients. Coefficients range from -1.00 to +1.00, with numbers closer to ±1.00 indicating stronger relationships. Attributions of cause and effect are not possible from correlational studies
- Cross-Sectional and Longitudinal Studies
Cross-sectional studies are conducted at one point in time and compare people of different ages, whereas longitudinal studies follow participants over an extended period of time. Cross-sectional studies can show differences between groups, but longitudinal studies can reveal developmental trends. This characteristic is an advantage of longitudinal studies, but they have the disadvantage of taking a long time and being expensive.
- Experimental Designs
Experimental designs can determine cause and effect relationships by manipulating an independent variable and observing the effect on a dependent variable, for example, comparing an experimental group on a low-fat diet (treatment group) to participants who maintain their regular diet (control group) and then measuring the development of cardiovascular disease (the dependent variable) in the two groups. Well-controlled experimental designs give scientists their best method to determine causation.
- Ex Post Facto Designs
Ex post facto designs are similar to experimental designs in that both use contrasting groups, but these designs do not include manipulation of independent variables. Instead, groups of participants differing on some subject variable (or participant variable) are contrasted to determine differences in the dependent variable. For example, contrasting people with varying levels of obesity to determine in food choices is an ex post facto study. The finding that heavier individuals express food preferences that differ from those of less obese individuals does not demonstrate that obesity is causally related to food preferences because ex post facto studies do not manipulate an independent variable or control for other factors.
III. Research Methods in Epidemiology
Epidemiology is a branch of medicine that investigates factors contributing to the occurrence of a disease in a particular population. Epidemiology evolved into a scientific discipline during the 19th century and played an important role in the fight against infectious diseases. Today, epidemiologists also study factors associated with chronic illness, including its prevalence and incidence. Prevalence is the proportion of the population affected by a particular disease at a particular time, whereas incidence is the number of new cases of a disease during a particular time, usually one year. Research methods used in epidemiology are similar to those employed by psychologists. Epidemiology research falls into three broad areas: observational methods, natural experiments, and experimental investigations.
- Observational Methods
Observational methods parallel correlation studies in psychology. The two types of observational methods are retrospective and prospective. Prospective studies are longitudinal designs that follow the forward development of a group of people starting an experience together. Retrospective studies begin with a group of people already experiencing a disease and then look for characteristics of these people that are different from those of people who do not have that disease. Retrospective studies are also called case-control studies because cases (people with a disease) are compared with controls (people not affected).
- Randomized, Controlled Trials
Randomized, controlled trials are equivalent to experiments in psychology. Clinical trials are randomized, controlled trials designed to test the effectiveness of a drug or treatment. Researchers assign participants to groups randomly to control for self-selection. Randomized, placebo-controlled double-blind designs are often considered the zenith of research design.
- Natural Experiments
Natural experiments are similar to ex post facto studies in psychology; both involve the selection rather than the manipulation of a variable. Natural experiments can be conducted when two similar groups of people naturally divide themselves into those exposed and those not exposed to a pathogen.
The statistical technique of meta-analysis allows researchers to evaluate many research studies on the same topic, even if the research methods differed. In addition, meta-analysis provides an index of the size of the effect, which allows researchers to gauge the importance of the effect.
- An Example of Epidemiological Research: The Alameda County Study
Epidemiology provides techniques for taking a first look at a health-related problem. An important example is the Alameda County Study, which began in 1965 in an effort to identify certain health practices that relate to subsequent mortality and morbidity. Alameda County researchers found that people who practiced six or seven basic health-related behaviors were less likely to die than those who practiced zero to three of these behaviors. These health practices included (1) getting seven or eight hours of sleep daily, (2) eating breakfast almost every day, (3) rarely eating between meals, (4) drinking alcohol in moderation or not at all, (5) not smoking, (6) exercising regularly, and (7) maintaining weight near the prescribed ideal.