Chapter 3: Evidence-Based Nutrition and Practice Flashcards
A proposed explanation for a problem or set of observations.
Hypothesis
The process of formulating explanations about the natural world and testing those explanations with experiments and data.
The Scientific Method
A three-pronged approach to working with clients, which consists of making decisions based on the weight of the scientific evidence, field observations, and individual client needs and preferences.
Evidence-Based Practice
Steps of the Scientific Method
1: Identify a problem or set of observations
2: Formulate a hypothesis
3: Design a study to test the hypothesis
4: Collect, synthesize, and interpret data
5: Discard or change hypothesis if data doesn’t support it OR continue testing data that supports the hypothesis.
An expected outcome generated from a hypothesis.
Prediction
True or False: Scientists identify what is most likely to be true by demonstrating what is not true.
True
A hypothesis or set of hypotheses for which a large body of high-quality evidence has been accumulated.
Theory
An account of a person’s experience or event.
Anecdote
A variable in an experiment that a scientist makes no effort to manipulate or account for.
Uncontrolled Variable
Original research where scientists perform experiments and collect data – this is in contrast to secondary research where scientists analyze data that has already been collected or published elsewhere.
Primary Research
Research in which a researcher observes ongoing behaviors to determine correlation.
Observational Research
A relationship between two or more variables.
Correlation
A type of scientific study/trial where participants are randomly assigned into different groups – one or more will be the intervention to be tested and one will be the control group. Groups are randomized and a control is used in an attempt to reduce potential bias in the trial.
Randomized Control Trial (RCT)
The variable scientists manipulate in an experiment.
Independent Variable
The ability to generalize the results of a study.
External Validity
A review where scientists systematically gather all research on a topic and evaluate it based on predefined criteria and rules.
Systematic Review
A statistical analysis of a group of studies to assess the overall weight of the evidence. It is an analysis of RCTs.
Meta-Analysis
What 2 reviews represent the highest evidence level because they give the consensus on the best research.
Meta-analysis (RCTs) and systematic review
True or False: A scientific theory is just a guess.
False
The scientific approach is _______ which means it is based on observation or experience.
Empirical
Case Studies, Surveys, Historical Research
3 Types of Descriptive Scientific Research
Cross-Sectional Studies, Case-control Studies, Cohort Studies
3 Types of Exploratory or Epidemiological Scientific Research
• Track a single person or group of people
over time
• Discuss characteristics of or events that
occur to a single person or group
• Primary limitation - may not be
generalizable to larger populations
Case Studies
• Questionnaires or interviews administered to samples of people • Primary limitation: • They collect self-reported data, and can be subject to bias • Potential issues with the reliability, validity, or how wording of questions can influence people’s answers
Surveys
Historical Research
• Looks at events that happened in the past and uses it to make inferences about other times, including the future • Limitations: • Information from the past may be incomplete or inaccessible • May be subject to the biases of the researchers involved
• Variables in a group at a specific point in time
• A cross-section of people
• Most useful for:
• Population-based surveys
• To assess the prevalence of diseases in a
population
• Primary limitation - impossible to assess
causal relationships because it’s a one-time
“snapshot” measurement
Cross-sectional Studies
• Determine if exposure to something is
associated with an outcome
• Scientists identify people with the outcome
and similar people who don’t have the
outcome
• Uses data that has already been collected or
occurred in the past
Case-control Studies
Group followed over time to
determine association between an exposure
and an outcome or disease
1. Cohort free of outcome or disease
2. Researchers identify exposure or event of
interest
3. Cohort followed over time until disease or
outcome occurs
4. Association between exposure and risk of
outcome assessed
• Limitations:
• Susceptibility to selection bias
• Subjects are followed for extended periods
of time may withdraw or be lost
follow-up
• If retrospective: less control over variables,
and that subjects may be susceptible to
recall bias
Cohort Studies
A sample of people under study is not representative of the larger population that scientists are looking to make inferences about.
Selection Bias
The critical evaluation of a study by other scientists. This is the highest quality source of scientific info.
Peer Review
Which of the following best describes an empirical scientific approach?
Controlled observation
Which of the following represents a weakness of observational studies?
Correlation does not equal causation
Which of the following best represents a weakness of interventional designs?
Small number of subjects
Scientists perform a study looking at the effects of caffeine on vertical jump performance. On one day, they give all the subjects caffeine followed by vertical jump tests. Two weeks later, they give all the subjects a placebo followed by the same vertical jump tests. Which term best describes this study design?
Crossover
Which item represents a high quality, non-peer reviewed source of information?
Academic Textbook
A scientist hypothesizes that a supplement will increase resistance training performance. A study is carried out, and the results do not support the hypothesis. Multiple studies by independent labs also fail to support the hypothesis. What is the appropriate response regarding the hypothesis?
The predictions have been falsified and the hypothesis is discarded.
Which term encompasses the weight of the scientific evidence, field observations, and individual client needs?
Evidence-based practice
Scientists randomly assign subjects to a low or high carbohydrate group and then look at changes in body weight over 3 months. Which item represents the independent variable in this study?
Diet type
Numerous studies, including genetic studies, randomized controlled trials on lipid lowering medications, and observational studies point to LDL having a causal role in heart disease. Which term best describes the concept that LDL plays a causal role in heart disease?
Theory
Scientists take 5000 people and have them fill out questionnaires on their dairy intake. They then compare cancer rates between people with high intakes and low intakes. What type of study is this?
Observational
Which of the following represents a strength of observational studies?
Large subject numbers
Scientists perform a study comparing 1000 women with breast cancer to 1000 women without breast cancer. They gather information on the women’s diets and look to see if the women diagnosed with breast cancer had more fat in their diet compared to the women who did not get cancer. Which term best describes this study?
Case-control study
Scientists gather 20 studies looking at the relationship between protein intake and lean body mass, and then they statistically analyze them together as a group. What type of study is this?
Meta-analysis
Which term describes a variable in an experiment for which a scientist takes no steps to account for?
Uncontrolled variable
Scientists find that a protein supplement increases lean mass in the elderly. However, they caution that the results may not apply to other populations, like younger people. What term best describes what the scientists are referring to?
External validity
Scientists perform a study tracking 10,000 people over a 10-year period. They look at their sugar intake at the beginning of the study and then see who develops diabetes over the study duration. Which term best describes this study?
Cohort
Which term describes the phenomena when a group does not represent the population a scientist is intending to study?
Selection bias
A scientist observes that people tend to perform better in a weight training session after consuming a pre-workout supplement. The scientist proposes that the caffeine in the supplement is increasing arousal, leading to increased performance. Which term best describes this scientist’s proposal?
Hypothesis
Which observational study design allows scientists to hypothesize a potential causal association?
Cohort study