Principles Of Dietetics - topic C: research applications Flashcards
steps in research
- identify a relevant and important topic: review published research literature related to the topic
- develop well-considered research question (who, what, how)
- clear, simple statement in a few words, in a complete grammatical statement - research question leads to a hypothesis
- measurable, specifies population being studied, time frame, type of relationship being examined, defines variables being studied, states level of statistical significance - prepare research protocol: methodology to solve the problem
- study design and checklists
meta analysis
is a formal, defined system that combines the results of numerous small studies to increase the strength of belief in the observed effect. Studies are of similar design, have defined inclusion and exclusion criteria, and are published peer-reviewed studies
meta-analysis - QUOROM
has proposed quality standards for the review and monitoring of systematic reviews and meta-analysis of randomized trials. Companion standards that suggest common evaluation criteria for clinical trials
meta-analysis - PRISMA
randomized control trials. PRISMA is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. PRISMA focuses on the reporting of reviews evaluating randomized trials, but can also be used as a basis for reporting systematic reviews of other types of research, particularly evaluations of interventions
meta-analysis - MOOSE
meta-analysis of Observational Studies in Epidemiology
meta-analysis - CONSORT
Common criteria (guidelines) for clinical trials
Research report - results
specific lab, clinical, objective or subjective findings
Research report - discussion
interpretation of results, comparison with other studies; may be combined with results. discussing the results addresses the research question, objective and hypothesis. places results in context of existing science, implications for future research or clinical practice, limitations and strengths
Research report - implications
how the information might be applied in practice
descriptive research
- describes state of nature at a point in time
- generates hypotheses regarding determinants of a condition or disease- does not prove cause and effect - describes a situation
descriptive research- surveys
research designed to describe and quantify characteristics of a defined population; defined time frame; pinpoints problems
descriptive research - correlation studies or ecological studies
describe and don’t prove
- compare frequency of events (or disease rates) in different populations with the per capita consumption of certain dietary factors (correlation between fish consumption and breast cancer incidence)
analytical research
- randomization is dividing people into treatment or control groups without bias
- experimental group receives the program or treatment
- control group does not receive the treatment or may receive a placebo which gives the aura but not the substance of a service, removing the possibility of a Hawthorne effect (positive response due to attention that participants receive). In a study of aspartame, sugar might be the placebo.
- program is successful if the experimental group has improved more than the control group
analytical research - gold standard
clinical nutrition studies: RCT (randomized controlled trial) with comparison placebo control group is the gold standard. this is considered the best for evaluating medical treatments, and intervention with one or more treatments.
analytical research - quasi-experimental design
time series - series of measurements at periodic intervals before the program begins and after the program ends (note worthy change). it shows whether measurements before and after the program are a continuation of previous patterns or whether they indicate a noteworthy change - no control group
analytical research - cohort studies
- sometimes called incidence studies tracking the frequency of new cases (newly diagnosed) of a disease
- cohort- any group whose members have something in common
- carried out over a long period of time (longitudinal), and prospective (future-oriented)
- can also be restrospective
analytical research - cross-sectional studies / prevalence
- all existing cases at that time (prevalence)
- one time data collection counting all of the cases of a specific disease among a group of people at a particular time.
- describes current events
IRB - institutional review board (under FDA)
committee established to review and approve research involving human subjects to ensure it is conducted within all ethical and federal guidelines
what do you need to do to be designated as an author or a manuscript in a biomedical journal?
you must have made substantial contributions to the design or analysis and the interpretation of the data.
statistical evaluation, interpretation and application - internal validity
tests whether the difference between the two groups is real (has the experimental group really performed differently) - how valid is it internally
statistical evaluation, interpretation and application - external validity
tests whether or not a generalization can be made from the study to a larger population - how valid is it externally
statistical evaluation, interpretation and application - analysis of variance - ANOVA
- validity 3 or more samples
- used when several (three or more products) compete against one another
- answers: are there one or more significant differences anywhere among the samples
statistical evaluation, interpretation and application - reliability
consistency or reproducibility of test results
- test then retest later; are the results similar? the more similar, the more reliable
statistical evaluation, interpretation and application - nominal variable
(non-ordered) - variables that fit into a category with no special order (gender, race, marital status, present or absent)
statistical evaluation, interpretation and application - rank order variable
(ordinal scale) - observations compared with each other and put in order, perhaps from best to worst, or state of disease from 1 to 4
statistical evaluation, interpretation and application - dependent vs. independent variables
dependent are outcomes; independent variables are what you manipulate in your study
- treatments for diseases are independent variables (you can change the treatment to affect the disease)
- effect cholesterol levels (independent) have on heart attacks (dependent)
statistical evaluation, interpretation and application - sampling - probability
uses randomization - select a sample form the whole population so the characteristics of each of the units approximates the characteristics of the whole population
statistical evaluation, interpretation and application - non-probability
no way of forecasting that each element in the population will be represented in the sample
measuring data distributions - measures of central tendency
- center of any mass of data
1. arithmetic mean - simple average. total the values of all observations and divide by the number of observations
2. median - midpoint. arrange observations from low to high; count the number of values. median is the value at the midpoint.
3 mode - most frequently occurring value; prediction most likely to be right. repeated number
measuring data distributions - measures of dispersion
- how values are distributed about the mean
1. range - difference between the lowest and highest values in the distribution
2. standard deviation - indicates degree of dispersion about the mean value of a distribution - about 2/3 (68%) of all observations in a normal distribution lie within 1 SD of the mean - this range is called M + 1 SD of the mean (Mean + 1 SD)
existence of relationships
- correlations are relationships between varying types of data
- value of r is always between -1 and 1
- the closer r is to 1 or -1, the closer the points tend to cluster about the line, and the stronger the degree of linear relationship
- 1.1 and 1.2 are not valid answers
- perfect agreement or positive correlation is +1.0; perfect negative correlation is -1.0
- r =1 positive slope upward to the right
- r = -1 negative slope upward to the left
- closer dots are to the line = stronger the pull
clinical significance
lower p-value, higher significance of results
double blind study
removes bias from research; neither the researcher nor the subject knows which group is receiving the treatment and which the placebo
mortality / morbidity
rate of death; state of disease
inferential statistics
techniques that allow conclusions to extend beyond an immediate data set; what is the probability that the results can be applied to a larger group; what can you infer from the results of your study
pilot study
scaled down version of the larger investigation; practice implementation, determine whether clinical trial, as planned, is feasible; are goals realistic and attainable? includes every step in the study, but done on a small test group. will the study plan work? formative evaluation
focus group
method of attaining information about a target group; small group who talk about the beliefs, opinions, problems; contributes attitudinal data; subjective
qualitative research / quantitative research
asks why and how (subjective); asks how many, how often (objective)
use of evidence analysis as a basis for practice decisions
evidence-based guidelines are developed by conducting a systematic review and then using the conclusion of the review to develop practice-based guidelines. subject matter experts and trained analysts summarize best available evidence. the AND evidence analysis library assists in answering questions that may arise during the provision of nutrition case. based on scientific evidence.
