Chapter 11: Reasoning About the Design and Execution of Research

Question 1

What is the scientific method? What are the steps to the scientific method?

Answer 1

The scientific method is a set of steps that defines the appropriate order of events to structure and carry out and experiment.

It is an established protocol for transitioning from a question to a new body of knowledge.

1. Generate a testable question.
2. Gather data and resources.
3. Form a hypothesis.
4. Collect new data.
5. Analyze the data.
6. Interpret the data and existing hypothesis.
7. Publish.
8. Verify results.

Question 2

What is a hypothesis?

Answer 2

A hypothesis is the proposed explanation or proposed answer to our testable question. It is often in the form of an if-then statement, which will be tested.

Question 3

Why is publication an important step in the scientific method?

Answer 3

Publication provides an opportunity for peer review.

Question 4

What is the FINER method?

Answer 4

Is the necessary research study going to be FEASIBLE

Do scientist find this question INTERESTING

Is this particular question NOVEL?

Would the study obey ETHICAL principles?

Is the question RELEVANT outside the scientific community?

Question 5

MCAT concept check scientific method 1.1 page 402

Sort by relevance.

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Question 6

MCAT concept check scientific method 1.1 page 402 question 2

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Question 7

MCAT concept check scientific method 1.1 page 402 question 3

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Question 8

What is basic science research?

Answer 8

Basic science research is the kind conducted in a laboratory and not on people and is generally the easiest to design because the experimenter has the most control.

Question 9

Why do we use controls in experiments?

Answer 9

In order to make generalizations about our experiments, we must make sure that the outcome of interest would not have occurred without our intervention, we use controls.

Question 10

What are positive controls? What are negative controls?

Answer 10

Positive controls are those that ensure a change in the dependent variable when it is expected. For example. In the development of a new assay for detection of HIV, administering the test to a group of blood samples known to contain HIV could constitute a positive control.

Negative controls and ensure no change in the dependent variable when no change is expected. For example. With the same assay, administering the test to a group of samples know not to contain the HIV virus could constitute a negative control.

Question 11

What is the placebo effect?

Answer 11

In drug trials, a negative control group is often used to assess for the placebo effect: an observed a reported change when an individual is giving a sugar pill or sham intervention.

Question 12

What is causality?

Answer 12

Causality is in if-then relationship. If the change in the independent variable always proceeds the change in the dependent variable, and the change in the dependent variable does not occur in the absence of the experimental intervention, the relationship is said to be causal.

Flipping a light switch causes the light to illuminate, smoking causes lung cancer, studying gets good grades.

Question 13

What is the independent variable, what is the dependent variable? Where can we find them on a graph?

Answer 13

Question 14

Do we find the independent variable on the X or Y axis? Do we find the dependent variable on the X or Y axis?

Answer 14

We find the independent variable on the X axis and the dependent variable on the Y axis.

Question 15

What is accuracy (validity)?

What is precision (reliability)?

Answer 15

Accuracy, also called validity, is the ability of an instrument to measure a true value.

Precision, also called reliability, is the ability of the instrument to read consistently, or within a narrow range.

Question 16

MCAT concept check basic science research page 407 question 1

An experiment with improperly tared (zeroed) mass balance would suffer from what type of error?

Answer 16

This experiment would likely have an accuracy error, but not a precision error. In other words, the scale would reliably read the same weight, but the weight it reads is not correct. This would lead to a bias in the results.

Question 17

MCAT concept check basic science research page 407 question 2

Answer 17

Concentration of sodium hydroxide is the independent variable. pH is the dependent variable.

Question 18

MCAT concept check basic science research page 407 question 3

What is the purpose of a control during experiments? What characteristic of experimental research would be reduced in the absence of a control?

Answer 18

Controls in experiments help to establish causality by demonstrating that the outcome does not occur in the absence of an intervention.

Controls are used to keep the manipulation of different systems as similar as possible, or as a known standard against which to judge an experimental manipulation. Without controls it is more difficult to establish causality.

Question 19

What is randomization?

Answer 19

Randomization is the method used to control for differences between subject groups in biomedical research. This determines the placement of each subject in either a control group that receives no treatment or sham treatment or one or more treatment groups.

Question 20

What is blinding? What is single blind? What is double blind?

Answer 20

There is the investigator, assessor, the subject. Investigator: boss person. Assessor: studies outcomes. Subject: participants.

Blinding is where an investigator does not have information about which group the subject is in.

Single blind experiments, only the patient or the assessor is blinded.

Double blind experiments, the investigator, subject, and assessor all do not know the subjects group.

Question 21

In biomedical research, data analysis must account for variables outside the dependent and independent variables considered including gender and age, lifestyle variables, such as smoking status, and body mass index.

Given this, what are confounding variables?

Answer 21

Confounding variables are factors that impact the study’s outcome and cause, but aren’t the primary variables of interest.

Question 22

What is a regression analysis?

Answer 22

A way of interpreting the relationship between independent (x axis) and dependent (y axis) by graphing.

Regression analysis is a statistical technique that assesses the relationship between two or more variables, including a dependent variable and one or more independent variables. They could be linear, parabolic, exponential, logarithmic, or other relationships.

Question 23

What are observational studies? What are the three categories of observational studies?

Answer 23

Observational studies do not demonstrate causality, but draw on available data and analyze it.

Cohort studies are those in which subjects are sorted into groups based on different risk factors. For example. A study in with 100 smokers and 100 non-smoker are followed for 20 years while counting the number of subjects who developed lung cancer in each group would be an example of a cohort study. This is a variety of a longitudinal study.

Cross-sectional studies attempt to categorize patients into different groups at a single point in time. For example. The study to determine the prevalence of lung cancer and smokers and non-smoker at a given point in time would be example of a cross-sectional study.

Case control studies 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 our particular risk factor. For example, example, a study in which 100 patients with lung cancer and 100 patients without lung cancer are assessed for their smoking history would be an example of a case control study.

Question 24

What is a cohort study. What kind of study is a cohort study? Give an example.

Answer 24

Cohort studies are observational studies. Cohort studies are those in which subjects are sorted into groups based on different risk factors. For example. A study in with 100 smokers and 100 non-smoker are followed for 20 years while counting the number of subjects who developed lung cancer in each group would be an example of a cohort study.

Question 25

What is a cross sectional study? What kind of study is a cross sectional study? Give an example.

Answer 25

Cross sectional studies are an observational study. Cross-sectional studies attempt to categorize patients into different groups at a single point in time. For example. The study to determine the prevalence of lung cancer and smokers and non-smoker at a given point in time would be example of a cross-sectional study.

Question 26

What is a case-control study? What kind of study is a case-control study? Give an example.

Answer 26

Case-control studies are an observational study. Case-control studies 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 our particular risk factor. For example, a study in which 100 patients with lung cancer and 100 patients without lung cancer are assessed for their smoking history would be an example of a case control study.

Question 27

What are Hills criteria?

Answer 27

Hills criteria describe the components of an observed relationship that increased the likelihood of causality in the relationship. Know that his criteria did not provide an absolute guideline on whether a relationship is causal; thus, for any observational study, the relationship should be described as a correlation. Temporality is the most important for potentially establishing causality. Temporality example: smoking (the exposure) must precede the cancer (the outcome). Hill explained that for an exposure-disease relationship to be causal, exposure must precede the onset of disease.

Question 28

Compare and contrast bias and confounding.

Answer 28

Bias and confounding are both error sources. Bias is a result of flaws in the data collection phase of an experimental or observational study. Confounding is an error during analysis.

Question 29

What is selection bias?

Answer 29

Selection bias is the most prevalent type of bias. Selection bias is when the subject used for the study are not representative of the target population. People who volunteer for a study in a particular area may be significantly different from people who do not volunteer. For example, someone volunteering for a drug trial that requires clinical visits may be healthier or more likely to benefit from the study than someone who does not volunteer because they cannot make it to the hospital.

Question 30

What is detection bias?

Answer 30

Detection bias results from educated professionals, using their knowledge in an inconsistent way. 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. For example, high blood pressure (hypertension) and diabetes mellitus are more common among individuals who are obese. Thus, a physician may screen patients who are obese for hypertension and diabetes at a higher rate than other patients, inflating the true value of the secondary measurement.

Question 31

What is confounding?

Answer 31

Confounding is a data analysis error. The data may or may not be flawed, but an incorrect relationship is characterized. For example, consider the statement: having natural red hair leads to a decreased pain tolerance and higher opiate tolerance. First, the statement implies a cause of relationship as a result of what would almost certainly be an observational study. Second, consider whether or not this is realistic. There is no likely causality between the two. However, a third variable, such as gene mutation, could potentially cause both parts of this statement. If one measured the degree of red hair, pigment, and the degree of pain into intolerance, there might be a very strong statistical relationship, but there is no cause of relationship between these two. These “third-party” variables are called confounding variables, or cofounders.

Question 32

MCAT concept check human subjects research 11.3 page 412 question 1 True or false. The researcher who failed to demonstrate temporality can still provide evidence for a causal relationship by satisfying the rest of hills criteria.

Answer 32

False. Temporality is the only necessary criterion from his criteria. If temporality is not satisfied, the relationship cannot be said to be causal. The addition of other criterion increases the probability of a causal relationship, assuming that temporality has not been invalidated.

Question 33

MCAT concept check human subjects research 11.3 page 412 question 2 How does observational research differ from experimental research?

Answer 33

Observational research does not involve manipulation of the subjects environment. It is generally less conclusive and more subjective than experimental research, which does involve manipulation of the subject or environment.

Question 34

MCAT concept check human subjects research 11.3 page 412 question 3 What is the difference between bias and confounding?

Answer 34

Bias is an error in data collection. Confounding as an error in data analysis. Bias is a systematic (unidirectional) error that occurs during this selection of subjects or the measurement and collection of data. Confounding is an error that occurs during data analysis, in which an association is erroneously drawn between two variables because of a shared connection to a third variable.

Question 35

There are four core ethical tenants in medicine. What are they?

Answer 35

Beneficence. The obligation to act in the patient’s best interest. Non-malfeasance. The obligation to avoid treatments or interventions in which the potential for harm outweigh the potential for benefit. Respect for patients autonomy. The responsibility to respect patient’s decisions and choices about their own healthcare. Justice. The responsibility to treat similar patients with similar care, and to distribute healthcare resources fairly.

Question 36

What is informed consent?

Answer 36

Respect for persons includes the process of informed consent, in which a patient must be adequately counseled on the procedures, risks and benefits, and goals of a study to make a knowledgeable decision about whether or not to participate in the study. Furthermore, the investigator cannot exert coercive influence over the subjects, or they will not be acting autonomously.

Question 37

What is the Belmont Report? What experiment was the primary impetus of the Belmont report.

Answer 37

The Belmont Report is a landmark document published by the national commission for the protection of human subjects of biomedical and behavioral research in 1979. Delineates the three necessary pillars of research ethics: respect for persons, justice, and a slightly more inclusive version beneficence.

Question 38

What are morally relevant differences regarding justice and treatment of patients? Provide examples.

Answer 38

Morally relevant differences are defined as those differences between individuals that are considered an appropriate reason to treat them differently. Age is a significant moral difference in ethical deliberations. All else being equal, a transplant that is as likely to benefit a young child or an older adult might be given to the child because of a longer life expectancy. Population size is often morally relevant in study design because a study that impacts a large population will generally have more potential to do good than one that impacts a small population. In contrast, race, ethnicity, sexual orientation, gender, identity, disability status, and financial status are generally not considered morally relevant differences. Religion may or may not be a valid, moral criterion, depending on the context. For example, certain interventions that are prohibited by a given religion or grounds to avoid that treatment in an individual of that religion, this is in keeping with patient autonomy.

Question 39

What is the concept of equipoise?

Answer 39

If it becomes evident that one treatment options is clearly superior before a study is scheduled to finish, the trial must be stopped because providing an inferior treatment is a net harm. Research should be conducted in the least invasive, painful, or traumatic way possible. In addition, in studies comparing to potential treatment options, one cannot approach the research with the knowledge that one treatment is superior to the other.

Question 40

MCAT concept check ethics 11.4 page 415 question 1 What is the difference between autonomy and medical ethics and respect for persons in research ethics?

Answer 40

Autonomy is simply the right of individuals to make decisions on their own behalf and have those decisions be respected. Respect for persons also requires honesty, confidentiality, informed consent, and freedom from coercion.

Question 41

MCAT concept check ethics 11.4 page 415 question 2 During study design, Company, wishing to market a drug to individuals with severe diabetes promotes to enroll only individuals with mild diabetes. Which principle of research ethics is the company violating? Are there any research concerns in this proposed study besides ethics?

Answer 41

The company is violating the principle of justice by choosing participants that are not part of the target population. The company is also introducing selection bias.

Question 42

MCAT concept check ethics 11.4 page 415 question 3 What are some populations that must receive special consideration for coercion?

Answer 42

Children, pregnant individuals, and prisoners are considered especially at risk for coercion, and thus are granted special protections.

Question 43

What is a population? What is a parameter?

Answer 43

A population is the complete group of every individual that satisfies the attributes of interest. Information that is calculated using every person in a population is called a parameter.

Question 44

What is a sample? What is a statistic?

Answer 44

A sample is any group taken from a population that does not include all individuals from the population. Ideally, samples will be representative of the population and there are several methods of ensuring this. Information about a sample is called a statistic. With comparatively large or repeated samples, statistics can be used to estimate population parameters. If only a single small sample is taken, then very little information can be gleaned about the population.

Question 45

What is internal validity? External validity (generalizability)?

Answer 45

Question 46

What is statistical significance? What is clinical significance?

Answer 46

In research, the primary marker of success is being able to generate results that are statistically significant, that is, not the result of random chance. Clinical significance is a notable or worthwhile change in health status as a result of our intervention.

Question 47

MCAT concept check research in the real world 1.5 page 417 question 1 What is the difference between internal validity and external validity?

Answer 47

Internal validity is the tenancy of the same experiment to produce the same results when repeated, and provides support for causality. External validity is the ability to take the information generated during research and apply it to a larger group. External validity is also called generalizability.

Question 48

MCAT concept check research in the real world 1.5 page 417 question 2 Why might small samples provide insufficient information about a population?

Answer 48

Small samples are subject to more random variation than large samples. If only one person is selected, that person may be an outlier, but if a much larger sample is selected, an outlier will have less of an effect on the results.

Question 49

MCAT concept check research in the real world 1.5 page 417 question 3 What qualities must a study have to provide justification for an intervention?

Answer 49

The study must have both statistical significance and clinical significance to provide justification for an intervention. A study without statistical significance may be the result of random chance, whereas one without clinical significance will not impact patients.

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Question 65

What is the Hawthorne effect?

Answer 65

The Hawthorne effect is a change in behavior as a result of the knowledge that one is being observed, and is only present with human subjects.