NTR 629 – Week 3 Descriptive Designs
Descriptive Studies • Uses data that are routinely collected for various purposes to study the occurrence of disease and its possible causes among groups of groups • Most appropriate for preliminary exploratory studies • Inferences drawn from studying groups are not necessarily true for individuals
Case Studies • Case Report • Observations on one subject • Case Series • Observations on more than one subject • Describe experiences and identify common variables associated with disease, condition, epidemic, nutritional care, outcome, etc. • Data sources include: • Medical record/chart review • Interviews • Questionnaires – broad range of factors Case study and series do not lead to a true ‘finding’ as observations could be due to chance.
Developmental Study • Longitudinal (age changes) • Vs. Cross sectional (age differences) • With or without follow-up studies.
Cross-Sectional Studies • Descriptive in nature. • “A group examined at one point of time. Thus the measure of the exposure of interest and the outcome of interest are measured at the same time and temporal sequence cannot be established.” (1) • A type of prevalence study. • Exposure and disease measures obtained at the individual level. • Both probability and non-probability sampling used. • Brummer B, Harris J, Gleason P, Boushey CJ, Sheean PM, Archer S, Van Horn L. Publishing nutrition research: A review of epidemiologic methods. J Am Diet Assoc. 2009;109:1728-1737.
Cross-Sectional Studies Uses Limitations Does not provide incidence data. Cannot study diseases of low frequency. Cannot determine temporality of exposure and disease Cannot determine causality • Hypothesis generation • Intervention planning • Estimation of the magnitude and distribution of a health problem
Correlational (Ecological) Study • Descriptive study. • Researcher investigates associations between variables during the same time period. • For example – the relationship between the vitamin C intake and the frequency of colds • May use secondary data bases, such as vital statistics, national health surveys, censuses, or researcher created surveys.
NTR 629 – Week 3 Descriptive Studies:Qualitative Research – Field/Ethnographic Studies
Why Qualitative Research? • Choose qualitative if… • Problem is “pre-theoretical” • Want to discover pertinent questions, variables, concepts, problems • Interest in process (how/why) as important as outcome • Very audience specific (narrow sample selection) • Want data on social context, structure, interactions (ex: and impact on food habits) • Seeking to understand behavior from the study participants’ frame of reference.
Interviewing Interviewing is usually defined as conversation with a purpose. Focus Group Interviewing Guided or unguided interviews addressing a particular topic of interest or relevance to the group and the researcher. Delphi Technique using questionnaires • The purpose of interviewing is to collect data. • Main types of Interviews: • Standardized uses the same set of predetermined questions for all interviews • Semi-standardized utilizes some predetermined questions, but the researcher is allowed to probe beyond prepared questions • Unstandardized interviewers must develop, adapt and generate questions and follow-up probes appropriate to the given situation and the central purpose of the investigation.
Observation • Observation • Rich description of systematic observation of events, people, or things • Participant observation (overt) • Nonparticipant observation (covert) • Participant • Researcher actually participates in the situation or the setting they are observing • Non-participant observation • Researchers do not participate in the activity but “sit on the sidelines”
Ethnographic Field Method • Ethnography is the science of cultural description. • Ethnographers enter the natural setting and immerse self in the culture, but remain an “observer” (or “participant observer”). • Researchers can examine various phenomena as perceived by participants and represent these observations as the “ethnographic account”. • It is a process that attempts to describe and interpret social expressions between people and groups. Provision of detailed narrative accounts of what goes on in the lives of the study population is the result of having maintained complete, accurate, and detailed field notes of observations and interviews over a relatively long period of time. • May result in development of new theories or models.