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Descriptive Designs

NTR 629 – Week 3

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.

1. 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.

Uses Hypothesis generation Intervention planning Estimation of the

magnitude and distribution of a health problem

Limitations Does not provide

incidence data. Cannot study diseases of

low frequency. Cannot determine

temporality of exposure and disease

Cannot determine causality

Cross-Sectional Studies

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.

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Descriptive Studies:Qualitative Research –

Field/Ethnographic Studies

NTR 629 – Week 3

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 is usually defined as conversation with a purpose. 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.

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

Interviewing

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.