Chapter 11 - Reasoning About the Design and Execution of Research

Question 1

Scientific Method Steps:

Answer 1

Generate a testable question

Gather data and resources

Form a hypothesis

Collect new data

Analyze the data

Interpret the data and existing hypothesis

Publish

Verify results

Question 2

Hypothesis:

Answer 2

proposed explanation or proposed answer to our testable question

In the form of an if-then statement, which will be tested in subsequent steps

Question 3

Experimentation:

Answer 3

manipulating and controlling variables of interest

Question 4

Observation:

Answer 4

involves no changes in the subject’s environment

Question 5

Finer method:

Answer 5

method to determine whether the answer to one’s question will add to the body of scientific knowledge in a practical way and within a reasonable time period

Question 6

Finer Method Questions:

Answer 6

Is the necessary research study going to be feasible?

Do other scientists find this question interesting?

Is this particular question novel?

Has someone asked this question before and published it?

Would the study obey ethical principles?

Is the question relevant outside the scientific community?

Question 7

Basic science research:

Answer 7

research conducted in a lab, not on people

Easiest to design b/c experimenter has the most control

Question 8

Control/standard:

Answer 8

acts as method of verifying results

Question 9

Positive controls:

Answer 9

those that ensure a change in the dependent variable when it is expected

Question 10

Negative controls:

Answer 10

ensure no change in the dependent variable when no change is expected

Question 11

Placebo effect:

Answer 11

an observed or reported change when an individual is given a sugar pill or sham intervention

Question 12

Independent variable vs, Dependent Variable:

Answer 12

Independent variable: variable that is manipulated

Dependent variable: variable that is measured or observed

Question 13

What needs to happen in order for a relationship to be considered causal?

Answer 13

If the change in the independent variable always precedes the change in the dependent variable, and the change in the dependent variable does not occur in the absence of experimental intervention, the relationship is said to be causal

Question 14

Accuracy (validity):

Answer 14

ability of an instrument to measure a true value

Ex: accurate scale should register a 170lb person as 170 pounds

Question 15

Precision (reliability):

Answer 15

ability of an instrument to read consistently, or within a narrow range

Question 16

Systematic error:

Answer 16

when bias is considered

Question 17

How to overcome error from random chance?

Answer 17

Random chance can also introduce error into an experiment

Can be overcome by using a large sample size

Question 18

Human Subjects Research:

1. consists of what
2. experimental approach

Answer 18

Consists of experimental and observational studies

Experimental Approach - b/c subjects are in a less-controlled conditions, the data analysis phase is more complicated than in laboratory studies

Question 19

Randomization:

Answer 19

method used to control for differences between subject groups in biomedical research

Uses an algorithm to determine the placement of each subject into either a control group that receives no treatment, or one or more treatment groups

Question 20

Blinded:

1. definition
2. what happens without blinding

Answer 20

1. means they do not have information about which group the subject is in
2. Without blinding, the placebo effect would be greatly reduced in the control group, but still present in the treatment group

Question 21

Single-blind experiments:

Answer 21

only the patient or assessor (person who makes measurements on the patients or performs subjective evaluations) is blinded

Question 22

Double-blind experiments:

Answer 22

the investigator, subject, and assessor all do not know the subject’s group

Question 23

Confounding variables:

1. types of Variables:

Answer 23

Binary: yes vs. no, better vs. worse

Continuous: amount of weight lost, percent improvement in cardiac output

Categorical: state of residence, socioeconomic status

Question 24

Regression analysis:

Answer 24

may demonstrate linear, parabolic, exponential, logarithmic or other relationships

Question 25

Observational studies: 1. what they are 2. three categories (just list)

Answer 25

1. draw on available data and analyze it 2. cohort studies, cross-sectional studies, case-control studies

Question 26

Observational studies - Cohort studies:

Answer 26

those in which subjects are sorted into two groups based on differences in risk factors (exposures), and then assessed at various intervals to determine how many subjects in each group had a certain outcome ## Footnote *Ex: a study in which 100 smokers and 100 nonsmokers are followed for 20 years while counting the number of subjects who develop lung cancer in each group*

Question 27

Observational studies - Corss-sectional studies:

Answer 27

attempt to categorize patients into different groups at a single point in time ## Footnote *Ex: a study to determine the prevalence of lung cancer in smokers and nonsmokers at a given point in time*

Question 28

Observational studies - Case-control studies:

Answer 28

start by identifying the number of subjects with or without a particular outcome, and then look backwards to assess how many subjects in each group had exposure to a particular risk factor ## Footnote *Ex: a study in which 100 patients with lung cancer and 100 patients without lung cancer are assessed for their smoking history*

Question 29

Hill's criteria: 1. what it is 2. criteria (just list)

Answer 29

1. components of an observed relationship that increase the likelihood of causality in the relationship 2. temporality strength dose-responsive relationship consistency

Question 30

Hill's Criteria - Temporality:

Answer 30

the exposure (independent variable) must occur before the outcome (dependent variable)

Question 31

Hill's Criteria - Strength:

Answer 31

as more variability in the outcome variable is explained by variability in the study variable, the relationship is more likely to be causal

Question 32

Hill's Criteria - Dose-responsive relationship:

Answer 32

as the study or independent variable increases, there is a proportional increase in the response

Question 33

Hill's Criteria - Consistency:

Answer 33

the relationship is found in multiple settings

Question 34

Bias:

Answer 34

result of flaws in the data collection phase of an experimental or observational study ## Footnote **Systematic error**

Question 35

Confounding: 1. what it is 2. third party variable

Answer 35

1. an error during analysis 2. Data may or may not be flawed, but an incorrect relationship is characterized Third party variables called c**onfounding variables or confounders** Third variable that could effect both variables

Question 36

Selection bias: 1. definition 2. volunteers

Answer 36

the subjects used for the study are not representative of the target population ## Footnote * People who volunteer may be vert different from people who do not volunteer* * May also apply in cases where one gender is more prevalent in a study than another* * Measurement and assessment of selection bias occurs before any intervention*

Question 37

Detection Bias: 1. results from what 2. influence of prior studies

Answer 37

1. results from educated professionals using their knowledge in an inconsistent way 2. Because prior studies have indicated that there is a correlation between two variables, finding one of them increases the likelihood that the researcher will search for the second * Ex: high blood pressure and diabetes mellitus are more common in the obese population; so a physician will screen obese population for these things more than a patient of healthy weight*

Question 38

Hawthorne effect (observation bias):

Answer 38

posits that the behavior of study participants is altered simply because they recognize that they are being studied ## Footnote *Ex: patients in a study for a given weight loss drug may begin exercising more frequently or make dietary changes*

Question 39

Ethical Tenets - Beneficence:

Answer 39

obligation to act in the patient's best interest **is must be our intent to cause a net positive charge for both the study population and general population, and we must do our best to minimize any potential harms** Research should be conducted in the least invasive, painful, or traumatic way possible

Question 40

Four core ethical tenents: (just list)

Answer 40

1. Beneficence 2. Nonmaleficence 3. Autonomy 4. Justice

Question 41

Ethical Tenets - Nonmaleficence:

Answer 41

obligation to avoid treatments or interventions in which the potential for harm outweighs the potential for benefit

Question 42

Ethical Tenets - Autonomy:

Answer 42

responsibility to respect patients' decisions and choices about their own healthcare

Question 43

Ethical Tenets - Justice:

Answer 43

responsibility to treat similar patients with similar care, and to distribute healthcare resources fairly

Question 44

Respect for persons:

Answer 44

includes the need for honesty between the subject and the researcher; prohibits deception

Question 45

Informed consent:

Answer 45

a patient must be adequately counseled on the procedures, risks and benefits, and goals of a study to make knowledgeable decision about whether or not to participate in the study Investigator cannot exert a coercive influence over the subjects Also includes the need to respect the subjects' wishes to continue with or cease participation in a study

Question 46

Vulnerable persons:

Answer 46

(children, pregnant women, prisoners) require special protections above and beyond those taken with the general population

Question 47

Justice - as it applies to selection and execution of research:

Answer 47

applies to both the selection of a research topic and the execution of the research **The only way to determine the selection of a research question to maintain justice is through random chance** When there is risk associated with a study, it must be fairly distributed so as to not unduly harm any group

Question 48

Morally relevant differences: 1. what they are 2. examples 3. what are not considered morally relevant differences

Answer 48

1. differences between individuals that are considered an appropriate reason to treat them differently 2. e*x: age, population size* 3. **Not considered:** ethnicity, sexual orientation, financial status

Question 49

Population:

Answer 49

complete group of every individual that satisfies the attributes of interest

Question 50

Parameter:

Answer 50

information that is calculated using every person in a population

Question 51

Sample: 1. what they are 2. must represent what 3. what is the gold standard

Answer 51

1. any group taken from a population that does not include all individuals from the population 2. Samples will be representative of the population 3. Random samples are considered the gold standard

Question 52

Statistic:

Answer 52

information about a sample Can be used to estimate population parameters

Question 53

Internal validity:

Answer 53

support for causality

Question 54

External validity (generalizability): 1. studies with low generalizability 2. studies with high generalizability 3. example

Answer 54

1. Studies with low generalizability have very narrow conditions for sample selection that do not reflect the target population 2. High generalizability have samples that are representative of the target population 3. *ex: a psoriasis study with low generalizability will have people only diagnosed within the year, high generalizability would have participants with a distribution of time since diagnosis*

Question 55

Statistically significant:

Answer 55

not the result of random chance

Question 56

Clinical significance:

Answer 56

notable or worthwhile change in health status as a result of our intervention