CHAPTER 7
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Questions and Answers

In the context of research, why is it crucial for subjects to provide "informed" consent?

  • To ensure that the research study is conducted ethically and with due regard for the well-being of participants (correct)
  • To protect individuals from harm and guarantee privacy during the study
  • To guarantee that subjects fully understand the research procedures and are comfortable with them
  • To ensure that participants are aware of the potential risks and benefits of participating in research

    • What is the primary purpose of committees established to review research proposals?

  • To safeguard the rights and well-being of both the researchers and the participants involved in the study (correct)
  • To evaluate the scientific merit of the proposed research and ensure its alignment with ethical guidelines
  • To approve or reject the proposed research based on its potential to advance knowledge and understanding in a specific field
  • To assess the feasibility of the research project and its potential for generating impactful results

    • According to the provided content, what is the purpose of the “Group Project Exercise”?

  • To provide students with practical experience in designing and conducting their own research projects
  • To expose students to the ethical considerations involved in conducting research involving human subjects
  • To encourage students to engage in critical thinking and apply statistical concepts to real-world scenarios (correct)
  • To introduce students to the principles of statistical analysis and data interpretation

    • What can be done to address data that does not appear to be normally distributed?

    <p>Transform the data using appropriate statistical techniques to make it more closely resemble a normal distribution (C)</p> Signup and view all the answers

    What does the statement "Personal standards vary and extreme experimentations have occurred" suggest about the history of research and its ethical guidelines?

    <p>Ethical considerations in research have not always been prioritized, leading to controversies and violations of human rights (B)</p> Signup and view all the answers

    In a matched pairs design, what is the main purpose of matching subjects?

    <p>To ensure that the treatment groups are balanced in terms of important characteristics. (D)</p> Signup and view all the answers

    What is the primary way that a 'double-blind' experiment helps reduce bias?

    <p>By preventing experimenters from knowing which treatment subjects are receiving. (B)</p> Signup and view all the answers

    How does the placebo effect impact the effectiveness of a treatment?

    <p>It can have both positive and negative effects on the effectiveness of the treatment, depending on the individual and the treatment. (B)</p> Signup and view all the answers

    What is the most appropriate way to measure the effectiveness of a treatment in a matched pairs design?

    <p>Comparing the within-subject differences between the treatments. (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a matched pairs design?

    <p>Subjects are randomly assigned to treatment groups. (D)</p> Signup and view all the answers

    What is the primary challenge addressed by using a double-blind experiment?

    <p>The potential for bias from both subjects and experimenters. (C)</p> Signup and view all the answers

    What does it mean to say that a treatment has a 'negative placebo effect'?

    <p>The treatment's effect is weaker than expected due to subjects' negative expectations. (B)</p> Signup and view all the answers

    Which of the following is the most relevant outcome measure for a study investigating the effectiveness of a treatment for seasonal allergies?

    <p>The number of days with allergy symptoms during the peak allergy season. (C)</p> Signup and view all the answers

    What is the primary reason why it is important to inform subjects about the potential treatments they may receive in a double-blind study?

    <p>To allow subjects to make an informed decision about whether or not to participate. (A)</p> Signup and view all the answers

    Which of the following is an example of a 'matched pairs' design?

    <p>A study testing the effectiveness of a new acne treatment on identical twins. (D)</p> Signup and view all the answers

    What term is used for the individuals who participate in an experiment?

    <p>Experimental units (D)</p> Signup and view all the answers

    Which of the following best describes a placebo in the context of experiments?

    <p>A false treatment given to one group (B)</p> Signup and view all the answers

    What is a key characteristic of a randomized, comparative experiment?

    <p>Subjects are assigned to treatments randomly (B)</p> Signup and view all the answers

    In a matched pairs design, how are subjects typically grouped?

    <p>Based on similar characteristics (C)</p> Signup and view all the answers

    Which of the following is a fundamental aspect of experimental design?

    <p>Multiple individuals should be studied to draw valid conclusions (D)</p> Signup and view all the answers

    What are factors in an experiment?

    <p>The conditions or variables that are manipulated (A)</p> Signup and view all the answers

    Which of the following best describes the principle of replication in experiments?

    <p>It involves conducting the same experiment multiple times (D)</p> Signup and view all the answers

    What mistake did Ronald Fisher identify regarding the previous experimental data on fertilizers?

    <p>Random assignment of treatments was not utilized (A)</p> Signup and view all the answers

    What is a key benefit of using a block design in experiments?

    <p>It accounts for differences between groups before randomization. (C)</p> Signup and view all the answers

    Which of the following statements about gastric freezing is true?

    <p>Subsequent experiments showed no significant difference between gastric freezing and placebo. (A)</p> Signup and view all the answers

    In a completely randomized experimental design, what is the main characteristic of the assignment process?

    <p>Individuals are randomly assigned to both groups and treatments without any restrictions. (C)</p> Signup and view all the answers

    What limitation does randomization help to address in comparing treatment effects?

    <p>It prevents biases that could affect the outcome of the study. (A)</p> Signup and view all the answers

    What aspect of randomized comparative experiments is critical for ensuring validity?

    <p>All variables should be controlled except for the treatment itself. (A)</p> Signup and view all the answers

    How did the approach of randomized comparative experiments impact the use of gastric freezing?

    <p>It demonstrated that gastric freezing had no significant advantage over a placebo. (D)</p> Signup and view all the answers

    What is the main role of factors in an experiment as described in the content?

    <p>They correspond to explanatory variables responsible for observed effects. (A)</p> Signup and view all the answers

    Why was gastric freezing widely used before being abandoned?

    <p>It appeared safe and initially reduced ulcer pain in many patients. (D)</p> Signup and view all the answers

    In which of the following scenarios would a block design be most appropriate?

    <p>When treatment effects are expected to vary significantly among different groups. (C)</p> Signup and view all the answers

    What was a primary reason for assigning fields randomly to receive fertilizer in the agricultural experiment?

    <p>To reduce the variability caused by soil type and moisture differences. (C)</p> Signup and view all the answers

    What is a characteristic of a double-blinded study?

    <p>Both the participants and researchers are unaware of the treatment assignments. (A)</p> Signup and view all the answers

    What could be a consequence of using a placebo in a clinical trial?

    <p>It may lead to ethical concerns regarding informed consent. (B), Participants may experience a psychological benefit. (D)</p> Signup and view all the answers

    Why is random sampling important in clinical research?

    <p>It ensures every individual in the population has an equal chance of selection. (D)</p> Signup and view all the answers

    What is a significant reason for adjusting drug dosage recommendations for different demographics, such as gender?

    <p>Women eliminate certain drugs more slowly than men. (B)</p> Signup and view all the answers

    In the provided experimental design examples, what was primarily measured after the runners consumed the drinks?

    <p>Protein synthesis (B)</p> Signup and view all the answers

    Which of the following best describes the ethical considerations in experimentation?

    <p>Researchers must evaluate the rights of all subjects, including animals and ecosystems. (D)</p> Signup and view all the answers

    What main issue is likely to arise from a lack of realism in a clinical study?

    <p>Overestimation of treatment benefits. (C)</p> Signup and view all the answers

    What is a potential drawback of conducting carcinogenicity studies on lab rats?

    <p>High doses may not reflect realistic human exposure. (D)</p> Signup and view all the answers

    What is the importance of random assignment in clinical trials?

    <p>It helps to evenly distribute characteristics across treatment groups. (C)</p> Signup and view all the answers

    Flashcards

    Experimental Units

    The individual subjects being studied in an experiment.

    Explanatory Variables

    Factors in an experiment that are manipulated to observe effects.

    Treatment

    Specific experimental condition applied to subjects in an experiment.

    Control Group

    A group in an experiment not receiving the treatment, used for comparison.

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    Randomized Experiments

    Experiments where subjects are randomly assigned to treatments to minimize bias.

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    Replication

    Studying several individuals to ensure results are consistent and reliable.

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    Completely Randomized Design

    An experimental design where all subjects are assigned treatments completely at random.

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    Double-Blind Experiment

    An experiment where both subjects and researchers do not know who receives the treatment.

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    Main Outcome Measure

    The primary indicator used to assess the effectiveness of a treatment, usually expressed quantitatively.

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    Matched Pairs Design

    An experimental design where subjects are paired based on similar characteristics and treatments are randomly assigned within each pair.

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    Placebo Effect

    The observed improvement in a patient's condition resulting from their belief in treatment rather than from an actual therapeutic intervention.

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    Negative Placebo Effect

    A reduction in effectiveness of an active treatment due to it being labeled as a placebo.

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    Blinding in Experiments

    The method of keeping participants and/or researchers unaware of the treatment assignments to reduce bias.

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    Therapeutic Results of Placebo

    The benefits observed from a placebo, which can affect a significant number of patients, up to 35%.

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    Random Assignment

    The process of assigning subjects to different treatments randomly to ensure groups are comparable.

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    Symptom-Free Days Measurement

    A way to quantify health improvement by counting days without symptoms, used in studies measuring treatment effectiveness.

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    Repeated Measures

    A research design where the same subjects are tested multiple times under different conditions.

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    Informed Consent

    A process ensuring subjects understand and agree to participate in research.

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    Normal Distribution

    A probability distribution that is symmetrical and bell-shaped, characterized by its mean and standard deviation.

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    Graphical Evidence

    Visual representations of data used to support claims about findings or distributions.

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    Transforming Data

    Applying mathematical operations to alter data to make it fit a normal distribution better.

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    Experimental Design Types

    Various structures for experiments including randomized, block, and matched pairs designs.

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    Randomized Comparative Experiment

    An experiment where subjects are randomly assigned to different treatments to compare outcomes.

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    Gastric Freezing

    A treatment where a balloon cools the stomach to alleviate peptic ulcers.

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    Placebo

    A substance with no therapeutic effect used as a control in experiments.

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    Block Design

    An experimental design that groups subjects with similar characteristics before randomization to control for variability.

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    Factors

    The explanatory variables in an experiment affecting the outcome.

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    Randomization

    The process of randomly assigning subjects to treatment groups to ensure fairness.

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    Comparative Analysis

    The process of comparing results from different treatment groups to evaluate effects.

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    Blinded Study

    An experiment where information is kept from participants to prevent bias.

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    Double-Blind Study

    An experiment where neither participants nor researchers know who gets treatment.

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    Therapeutic Kinesio Tape

    A type of tape used in therapy often thought to alleviate pain.

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    Efficacy

    The ability to produce a desired or intended result in an experiment.

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    Sample Representativeness

    How well a sample reflects the population it is drawn from.

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    Experimental Design

    The plan for how an experiment will be conducted, including its structure and procedures.

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    Carcinogenicity Studies

    Research evaluating the cancer-causing potential of a substance.

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    Ethics in Experimentation

    The moral principles guiding experiments on humans, animals, and ecosystems.

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    Study Notes

    Course Information

    • Course title: BMS 511 Biostats & Statistical Analysis
    • Chapter number: 7
    • Chapter topic: Designing experiments
    • Instructor: Guang Xu, PhD, MPH
    • Institution: Marian University
    • Copyright: © 2018 W. H. Freeman and Company

    Previous Learning Objectives

    • Samples and observational studies
    • Observational study vs. experiment
    • Population vs. sample
    • Randomness and bias
    • Simple random sample (SRS)
    • Other probability samples
    • Sample surveys
    • Comparative observational studies

    Learning Objectives

    • Terminology of experiments
    • Randomized, comparative experiments
    • Completely randomized designs
    • Block designs
    • Matched pairs designs
    • Double-blind experiments
    • Ethics and experimentation

    Terminology

    • Experimental units: Individuals in an experiment. Subjects if they are human.
    • Factors: Explanatory variables
    • Treatment: Specific experimental condition applied to subjects. Combination of several factors. Examples include administering a drug, or placing someone on a diet/exercise program.

    Randomized, Comparative Experiments

    • Compare response to a given treatment to:
      • Another treatment
      • The absence of treatment (control)
      • A placebo (fake treatment)
    • Subjects assigned to treatments randomly
    • Replication: Several or many individuals studied

    Inventing experimental design

    • Ronald Fisher's work with fertilizer application to evaluate effects in farming.
    • Fertilizer applied to one field vs. not applied to a nearby field in same year.
    • Satellite and soil recordings show soil types and moisture vary even within a field.
    • Solution: randomizing comparative experiments. Selecting many fields and randomly assigning to receive fertilizer or not. Grain yield compared.

    Importance of Design

    • Gastric freezing used to treat peptic ulcers.
    • Patients swallowed a balloon with refrigerated liquid to cool their stomach.
    • Later randomized comparative experiment found no significant difference between gastric freezing and placebo.
    • Importance of experimental design in ensuring reliable results.

    Completely randomized designs

    • Individuals randomly assigned to groups, then to treatments completely at random. Example: rats assigned to new diet vs. standard diet; weight gain compared between groups.

    Block designs (1 of 2)

    • Subjects divided into blocks sharing a given characteristic to account for differences between blocks.
    • Explanatory variables called factors.
    • Blocks are not random; randomization occurs within each block.
    • Design choice allows control over number of individuals receiving each treatment in each block.

    Block designs (2 of 2)

    • Example: 530 children enrolled, 285 smoke exposed; 140 school-based care plus ETS program, 145 usual care.
    • 245 not smoke exposed; 125 school-based care, 120 usual care.
    • Outcome: Mean number of symptom-free days per 2 weeks (November-February), assessed by blinded interviews.

    Matched pairs designs

    • Choose pairs of subjects closely matched (e.g., twins).
    • Randomly assign who receives which treatment within each pair.
    • Alternatively, give two or more treatments to each subject in random order. Repeated measures for each subject.
    • Examples include giving two chili bowls (version A and B) and subjects rating them.

    Placebo effect (1 of 2)

    • Improvement in health/perceived condition may be due to belief of being cared for, not necessarily active treatment.
    • Therapeutic results can be up to 35% of patients.
    • Examples include famous placebo interventions (kiss, blow, hug) helping kids cope with minor injuries.
    • Spinal cord response to placebo seen early. Negative placebo effect also occurs (labeling active drug a placebo lowers its effectiveness).

    Placebo effect (2 of 2)

    • Direct evidence for spinal cord involvement in placebo analgesia.
    • Altered placebo and drug labeling changes outcome of episodic migraine attacks.

    Double-blind experiments

    • Bias (conscious or unconscious) from placebo effect, or experimenter, is a challenge.
    • "Blinding" helps against bias.
    • Subjects and experimenters don't know who received which treatment until the experiment is completed.
    • However, subjects must be informed and consent.

    Examples of blinded studies (1 of 2)

    • Clinical efficacy of Kinesio tape for shoulder pain. Randomized, double-blinded, clinical trial.
    • Acupuncture efficacy for migraine prophylaxis. Single-blinded, double-dummy, randomized controlled trial.

    Examples of blinded studies (2 of 2)

    • Figures showing therapeutic Kinesio Tape and sham Kinesio Tape application.

    Experimental design examples

    • Six male runners in two trials, consuming either chocolate milk or sports drink. Measured protein synthesis.
    • Study of sickle-cell anemia. 152 patients given hydroxyurea; 147 given a placebo (dummy pill). Pain episodes counted at the end of the study.

    Lack of realism (1 of 2)

    • Is the sample representative of the target population?
    • Random sampling used to gain info about populations.
    • FDA protecting and promoting health.

    Lack of realism (2 of 2)

    • FDA requiring lower dose for certain sleep drugs (zolpidem) due to women eliminating it slower.
    • Carcinogenicity studies. High doses of potential carcinogens used in lab rats. Results not always applicable to humans (e.g., saccharin).

    Ethics and experimentation

    • Biological experimentation has an impact on life (live subjects and ecosystems). Rights of human subjects, animals, and ecosystems.
    • Physical vs. ethical limits in experiments.
    • Placebo groups, experiment interruptions.
    • Varying personal opinions; extreme experimentation done in the past.
    • Committees now to review proposals, and subjects need informed consent.

    Short Break!

    SPSS software

    • Descriptive statistics, frequencies, correlation analyses, and more
    • Other analysis types included regressions, generalized linear models, mixed models, and more

    Exercise 1

    • Check if datasets are normally distributed.
    • Provide graphical evidence to support claims.
    • Transform if necessary.
    • Datasets to be copied and pasted into chosen software for analysis.

    Exercise Data

    • Data set for practice on normal distribution.

    Group Project Exercise

    • Apply learned statistics and critical analysis.
    • Evaluate study's story, methods, results, conclusions, future.

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    BMS 511 Biostats & Statistical Analysis PDF

    Description

    Test your understanding of experimental design principles covered in Chapter 7 of BMS 511 Biostats & Statistical Analysis. This quiz focuses on randomized experiments, completely randomized designs, block designs, and ethics in experimentation. Challenge yourself with terminology and concepts essential for designing effective experiments.

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