Research Methods in Epidemiology

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Questions and Answers

What are observational studies?

The researchers do not change anything; they just gather information. The results measure association or correlation on causation.

What do prospective studies entail?

Collect data then wait for outcomes, with key outcomes measured after exposure.

What does retrospective imply in research?

Outcome is measured before exposure.

What characterizes cross-sectional studies?

They provide a 'snapshot' of exposures and outcomes at the same time. Signup and view all the answers

How do case-controlled studies work?

They assess outcome first, then work backward to measure exposure. Signup and view all the answers

What does a cohort study measure?

Exposure measured before the outcome develops, can be prospective or retrospective. Signup and view all the answers

What are experimental studies?

Research that manipulates the environment. Signup and view all the answers

What does a positive correlation indicate?

X and Y increase or decrease together. Signup and view all the answers

What does a negative correlation mean?

As one variable increases, the other decreases. Signup and view all the answers

What is correlation represented by?

r, which ranges from -1 to +1. Signup and view all the answers

What is a paired comparison test?

A preference test with 2 samples rated for qualities. Signup and view all the answers

What is a triangle test?

Involves 2 of the same sample and 1 different sample for identification. Signup and view all the answers

What is a quantitative descriptive test?

Involves 8-12 panelists trained on sensory characteristics. Signup and view all the answers

What do evidence grades indicate?

I= Strong, IV= Weak/expert opinion, V= Insufficient evidence. Signup and view all the answers

What is quantitative data?

Information that can be measured and written in numbers. Signup and view all the answers

What does qualitative data explain?

Information about behavior, such as childhood experiences around food. Signup and view all the answers

What is validity in research?

The extent to which a test measures or predicts what it is supposed to. Signup and view all the answers

What does reliability refer to?

The degree to which an assessment tool produces stable and consistent results. Signup and view all the answers

What is bias in research?

Related to accuracy and validity; a systematic error. Signup and view all the answers

What is random error associated with?

Precision and reliability. Signup and view all the answers

What does sensitivity in testing refer to?

The ability to identify a positive diagnosis. Signup and view all the answers

What does specificity in testing indicate?

The ability of a test to identify those without the diagnosis. Signup and view all the answers

What is prevalence in a medical context?

The number of existing diagnosis cases during a period of time. Signup and view all the answers

What does incidence refer to?

The number of new cases that develop over a period of time. Signup and view all the answers

What is an odds ratio?

A measure of association between a dependent and independent variable. Signup and view all the answers

What does a negative skew indicate?

The mean is lower than the median. Signup and view all the answers

What does a positive skew indicate?

The mean is higher than the median. Signup and view all the answers

What is descriptive research?

Research that does not determine a relationship; qualitative in nature. Signup and view all the answers

What is analytic research?

Research that focuses on finding causes, including experimental and observational studies. Signup and view all the answers

What are nominal variables?

Variables that have no order, e.g., gender, race. Signup and view all the answers

What is an ordinal scale?

A scale of measurement where categories form a rank order along a continuum. Signup and view all the answers

What does numerical discrete data refer to?

Data with numbers that do not have a set number, like the number of clinic visits. Signup and view all the answers

What is numerical continuous data?

Data that falls on a continuum, e.g., height, weight, time. Signup and view all the answers

What does standard deviation measure?

The dispersion of data about the mean. Signup and view all the answers

What do P values indicate?

P ≤ 0.05 is significant; the lower the P value, the higher the statistical significance. Signup and view all the answers

What is a nasogastric tube?

A tube inserted through the nose into the stomach, used for less than 4 weeks. Signup and view all the answers

What is nasoduodenal/nasojejunal access?

Access running from the nose to the small intestines, used for less than 4 weeks. Signup and view all the answers

What are gastrostomy and jejunostomy tubes used for?

They are surgically placed and used when patients cannot have a tube through their mouth or throat. Signup and view all the answers

What does PEG/PEJ stand for?

Percutaneous endoscopic gastrostomy/jejunostomy, which can last months to years. Signup and view all the answers

What are G tubes prone to?

Leakage, skin irritation, nausea, vomiting, and bloating. Signup and view all the answers

What issues are associated with J tubes?

Increased diarrhea and no bolus feeds, requiring elemental formulas. Signup and view all the answers

What is post pyloric access used for?

To avoid stimulating the pancreas, often after gastrointestinal surgery. Signup and view all the answers

What are indications for J tubes?

Gastroparesis, increased risk of aspiration, and other gastrointestinal disorders. Signup and view all the answers

What does digestion and absorption depend on?

The formula depends on where the tube ends. Signup and view all the answers

What happens as a result of gut atrophy?

Leads to leaky channels, malformed villi, and inflamed intestinal cells. Signup and view all the answers

What are transitional diets?

Clear liquid and full liquid diets. Signup and view all the answers

What is dumping syndrome?

Occurs when hypertonic contents enter the small intestine, causing various symptoms. Signup and view all the answers

What is a polymeric formula?

Intact standard formula containing whole proteins, complex carbs, and long-chain triglycerides. Signup and view all the answers

What does a monomeric formula contain?

Hydrolyzed components like free amino acids or essential fatty acids. Signup and view all the answers

What is a hypertonic formula?

Contains a high concentration of solute than the solution. Signup and view all the answers

What characterizes small bowel syndrome?

Inadequate length of the small intestine for proper nutrient absorption. Signup and view all the answers

What are glutamine-containing formulas designed to do?

Meet increased glutamine requirements during stress. Signup and view all the answers

What do added fiber formulas do?

Help normal bowel function for those with constipation or diarrhea. Signup and view all the answers

What are controlled CHO formulas used for?

Low carbohydrate, high-fat formulas to aid ventilator weaning. Signup and view all the answers

What is PN?

Parenteral nutrition used when patients have intestinal failure. Signup and view all the answers

What does central PN access involve?

Delivery to the superior vena cava or right atrium via catheter. Signup and view all the answers

What is peripheral PN access?

Not used for more than 10-14 days, maintains osmolarity below 900-1,100. Signup and view all the answers

How to calculate osmolarity?

Use the formula: dextrose g/L x 5 + AA g/L x 10 + 300-400. Signup and view all the answers

What is the maximum glucose infusion rate (GIR)?

5 mg/kg/min or over 0.36 g x kg x 24. Signup and view all the answers

What do nitrogen ratios indicate?

80:1 for critically ill, 100:1 for those with difficulty maintaining muscle mass, 150:1 for unstressed stable patients. Signup and view all the answers

What percentage of lipid calories should come from lipids?

2-4% of total estimated calories. Signup and view all the answers

What is the hang time for an open system?

4-8 hours. Signup and view all the answers

What is the hang time for a closed system?

24-48 hours. Signup and view all the answers

What is refeeding syndrome?

Low serum levels of potassium, magnesium, and phosphorus resulting from too-rapid infusion of carbohydrates. Signup and view all the answers

What is a colloid?

A mixture containing small, undissolved particles that do not settle out. Signup and view all the answers

What does a suspension contain?

A mixture where particles can be seen and easily separated by settling or filtration. Signup and view all the answers

What is a Tyndall test used for?

To shine light into mixtures to identify components. Signup and view all the answers

What is a foam?

Air dispersed in liquid, like whipped cream. Signup and view all the answers

What is an emulsion?

A mixture of oil and water. Signup and view all the answers

What is a sol?

A solid dispersed in a liquid, such as gelatin in water. Signup and view all the answers

What is a gel?

A liquid dispersed in a solid. Signup and view all the answers

What are water facts associated with?

Heat of fusion, adding salt or sugar lowers freezing point, increasing boiling point; water activity required for bacteria survival. Signup and view all the answers

What is the function of sugar?

Sweetness, aroma, fermentation, texture and structure, browning and caramelization. Signup and view all the answers

What characterizes cereals and flours?

Enriched means nutrients lost during processing are added back; fortification adds higher levels than naturally occurring. Signup and view all the answers

What are the five mother sauces?

Tomato, hollandaise, bechamel, espagnole, veloute. Signup and view all the answers

What are the types of pasteurization?

Low temp (vat), high temp short time (HTST), higher heat shorter time (HHST), ultra pasteurization (UP), and ultra-high temp (UHT). Signup and view all the answers

What is the reference protein in nutrition?

Eggs, which contain avidin and choline. Signup and view all the answers

What influences the melting point of lipids?

Factors include the length of the carbon chain, saturation, configuration, and crystalline formation. Signup and view all the answers

What are leavening agents?

Baking soda requires acid to activate; baking powder contains both baking soda and an acid. Signup and view all the answers

What problems arise in baking?

Overmixing leads to tunnels, peaked tops, pale crust; undermixing leads to low volume, flat tops. Signup and view all the answers

What constitutes a standard drink?

12 oz beer, 5 oz wine, or 1.5 oz spirits. Signup and view all the answers

What governs USDA grading for fruits and vegetables?

Grading is voluntary and considers color, shape, size, maturity, and defects. Signup and view all the answers

How is milk and dairy graded?

Graded by bacterial count. Signup and view all the answers

Study Notes

Observational Studies

Researchers gather information without manipulating variables; focus on association rather than causation.

Prospective Studies

Involves collecting data and monitoring outcomes over time; often used to detect pre-symptomatic conditions, e.g., heart disease prior to cardiac events.

Retrospective Studies

Evaluate outcomes that have already occurred before assessing exposure.

Cross-Sectional Studies

Provide a "snapshot" of data on exposures and outcomes simultaneously, exemplified by studies like NHANES.

Case-Controlled Studies

Begin with outcomes, then investigate past exposures by comparing affected individuals to controls.

Cohort Studies

Measure exposure first, observing outcomes later; can be either prospective or retrospective.

Experimental Studies

Involve manipulation of the study environment; randomized studies can infer causation, unlike non-randomized studies.

Correlation Types

Positive correlation: both variables move in the same direction.
Negative correlation: one variable increases while the other decreases.
Correlation coefficient (r) ranges from -1 to +1, with 0 indicating no relationship.

Sensory Evaluation Tests

Paired comparison test: judges assess two samples for preference.
Triangle test: judges identify a different sample among two identical ones.
Quantitative descriptive test: trained panelists rate samples based on sensory characteristics.

Evidence Grades

Evidence is graded I (strong) to IV (weak/expert opinion), with V indicating insufficient evidence.

Data Types

Quantitative data: measurable information presented in numerical form (e.g., clinical visits).
Qualitative data: descriptive insights focused on behaviors and experiences.

Validity and Reliability

Validity: extent to which tests measure intended outcomes (internal vs. external validity).
Reliability: consistency of assessment tools; stable results indicate high reliability.

Errors in Measurement

Bias: systematic error impacting accuracy and validity.
Random error: affects precision and reliability.

Diagnostics

Sensitivity: ability of a test to correctly identify positive cases (100% sensitivity means no false negatives).
Specificity: ability to identify those without the disease.

Epidemiologic Metrics

Prevalence: existing cases of a disease within a given time frame.
Incidence: number of new cases developing over a specified period.

Statistical Analysis

Odds ratio: measures association between dependent and independent variables.
P-values: significance threshold; P≤0.05 indicates statistical significance.

Nutritional Support

Nasogastric tubes and nasoduodenal/nasojejunum tubes are short-term feeding options.
Gastrostomy and jejunostomy provide long-term access when oral function is inadequate.

Feeding Formulas

Polymetric formulas include whole proteins and complex carbohydrates.
Monomeric formulas consist of hydrolyzed proteins for easier absorption.
Glutamine-containing formulas enhance recovery during stress phases.

Parenteral Nutrition (PN)

Used in cases of intestinal failure with different access methods: central and peripheral.
Glucose infusion rate (max: 5 mg/kg/min) and nitrogen ratios vary by patient condition.

Lipid Administration

Must balance caloric needs with lipid intake; recommended limits for critically ill patients.

Food Science

Key components of sauces: five mother sauces crucial in culinary applications.
Pasteurization methods vary in temperature and time, affecting food safety.

Baking Essentials

Overmixing and undermixing can significantly affect baked goods' texture and volume.

Alcohol Guidelines

Defined measures for different alcoholic beverages in standard servings.

USDA Grading

Voluntary grading system assesses fruits and vegetables on defects and quality.

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Description

This quiz covers various types of epidemiological studies, including observational and experimental methods. It delves into details such as prospective, retrospective, and cross-sectional studies, helping you understand their unique characteristics and applications. Test your knowledge of how these methods are used to gather data and determine correlations in health research.