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CHAPTER 1.3
| Question | Answer |
|---|---|
| When we describe a ----- or way of thinking as scientific, we mean it's based on assumptions and methods that yield reliable, objective, testable information about nature (fig. 1.3). | research method |
| The assumptions of ---are ideas that have proven fruitful in the past—for example, the idea that natural phenomena have natural causes, that nature is predictable and understandable, and that humans are a product of nature and subject to its laws. | science |
| Scientific method is highly variable | It refers not to formulaic observational procedures, but to certain habits of disciplined creativity, careful observation, logical thinking, and honest analysis of one's observations and conclusions. |
| Science ----- habits of inquiry meant to arrive at truthful representations of nature—objective conclusions that will stand up to efforts to find fault with them. | cultivates |
| Its conclusions are not infallible, but are always open to correction and refinement when new evidence demands it. | Science |
| The ---- is a process of making numerous observations until one feels confident in drawing generalizations and predictions from them. | inductive method |
| What we know of anatomy is a product of the | inductive method |
| We describe the normal structure of the body based on ---- | observations of many bodies |
| This raises the issue of what is considered proof in science. | Inductive Method |
| Inductive Method | We can never prove a claim beyond all possible refutation. |
| We can, however, consider a --- as proven beyond reasonable doubt if it was arrived at by reliable methods of observation, tested and confirmed repeatedly, and not falsified by any credible | statement |
| In science, all truth is tentative | ; there's no room for dogma |
| We must always be prepared to abandon ----- if tomorrow's facts disprove it. | yesterday's truth |
| Most physiological knowledge was obtained by the | hypothetico-deductive method |
| An investigator begins by asking a question and formulating a --- an educated speculation or possible answer to the question. | hypothesis |
| A good --- must be (1) consistent with what is already known and (2) capable of of being tested and possibly falsified by evidence. | hypothesis |
| Falsfibility | means that if we claim something is scientifically true, we must be able to specify what evidence it would take to prove it wrong |
| The --- thought the the gods or invisible demons caused epilepsy | ancients |
| Today ---- are attributed to bursts of abnormal electrical activity in nerve cells of the brain. | epileptic seizures |
| The claim that epilepsy is caused by abnormal electrical activity in the brain is falsifiable because it can be tested and potentially disproven with evidence, such as EEG readings showing electrical patterns during seizures. | EEG |
| Hypothesis | The purpose of a ---- is to suggest a method for answering a question. |
| The purpose of a --- is to suggest a method for answering a question. | hypothesis |
| From the ----, a researcher makes a deduction, typically in the form of an “if-then" prediction: If my hypothesis on epilepsy is correct and I record the brain waves of patients during seizures, then I should observe abnormal bursts of activity. | hypothesis |
| A properly conducted experiment yields ---- that either support a hypothesis or require the scientist to modify or abandon it, formulate a better hypothesis, and test that one. | observations |
| Hypothesis | testing operates in cycles of conjecture and disproof until one is found that is supported by the evidence. |
| Doing an experiment properly involves several important considerations. | What shall I measure and how can I measure it? |
| Doing an experiment properly involves several important considerations. | What effects should I watch for and which ones should I ignore? |
| Doing an experiment properly involves several important considerations. | How can I be sure my results are due to the variables that I manipulate and not due to something else? |
| Doing an experiment properly involves several important considerations. | When working on human subjects, how can I prevent the subject's expectations or state of mind from influencing the results? |
| Doing an experiment properly involves several important considerations. | How can I eliminate my own biases and be sure that even the most skeptical critics will have as much confidence in my conclusions as I do? |
| Several elements of experimental design address these important considerations: | Controls |
| Several elements of experimental design address these important considerations: | Psychosomatic effects |
| Several elements of experimental design address these important considerations: | Experimenter bias |
| Several elements of experimental design address these important considerations: | Statistical testing |
| Sample Size | The number of subjects (animals or people) used in a study is the sample size. An adequate sample size controls for chance events and individual variations in response and thus enables us to place more confidence in the outcome. |
| Sample Size | For example, would you rather trust your health to a drug that was tested on 5,000? Why? |
| Controls | Biomedical experiments require comparison between treated and untreated individuals so that we can judge whether the treatment has any effect. |
| A ---- consists of subjects that are as much like the treatment group as possible except with respect to the variable being tested. | control group |
| In one study, volunteers with high cholesterol were each given 800 mg of garlic powder daily for 4 months and exhibited an average 12% reduction in cholesterol. Was this a significant reduction, and was it due to the garlic? | It's impossible to say without comparison to a control group of similar people who received no treatment. In this study, the control group averaged only a 3% reduction in cholesterol, so garlic seems to have made a difference |
| Psychosomatic effects | Psychosomatic effects (effects of the subject's state of mind on his or her physiology) can have an undesirable effect on experimental results if we don't control for them. |
| In drug research, it is therefore customary to give the control group a ---- (pla-SEE-bo)—a substance with no significant physiological effect on the body. | placebo |
| If we were testing a drug, for example, we could give the - group the drug and the - group identical sugar tablets. Neither group must know. If it doesn't work for either, then it doesn't work. | treatment; control |
| Experimenter bias | In the competitive, high-stakes world of medical research, experimenters may want certain results so much that their biases, even subconscious ones, can affect their interpretation of the data. |
| double-blind method | On way to control the competitive, high-stakes world of medical research, experimenters may want certain results so much that their biases, even subconscious ones, can affect their interpretation of the data. |
| double-blind method | In this procedure, neither the subject to whom a treatment is given nor the person giving it and recording the results knows whether that subject is receiving the experimental treatment or the placebo. |
| double-blind method | A researcher may prepare identical-looking tablets, some with the drug and some with placebo; label them with code numbers; and distribute them to participating physicians. |
| double-blind method | The physicians themselves don't know whether they're administering drug or placebo, so they can't give the subjects even accidental hints of which substance they're taking. |
| double-blind method | When the data are collected, the researcher can correlate them with the composition of the tablets and determine whether the drug had more effect than the placebo. |
| Statistical testing | If you tossed a coin 100 times, you would expect it to come up about 50 heads and 50 tails. If it actually came up 48:52, you would probably attribute this to random error rather than bias in the coin. |
| Statistical testing | But what if it came up 40:60? At what point would you begin to suspect bias? |
| Statistical testing | This type of problem is faced routinely in research-how great a difference must there be between control and treatment groups before we feel confident that it was due to the treatment and not merely random variation? |
| Statistical testing | What if a treatment group exhibited a 12% reduction in cholesterol level and the placebo group a 10% reduction? Would this be enough to conclude that the treatment was effective? |
| Statistical testing | Scientists are well grounded in statistical tests that can be applied to the data—the chi- square test, the t test, and analysis of variance, for example. |
| Statistical testing | A typical outcome of a statistical test may be expressed, "We can be 99.5% sure that the difference between group A and group B was due to the experimental treatment and not to random variation." truth, but in statements of probability. |
| Statistical testing | Science is grounded not in statements of absolute truth, but in statements of probability |
| Peer Review - When a scientist applies for funds to support a research project or submits results for publication, the application or manuscript is submitted to peer review—a critical evaluation by other experts in that field. | Peer Review |
| Even after a report is published, if the results are important or unconventional, other scientists may attempt to reproduce them to see if the author was correct. | Peer Review |
| At every stage from planning to postpublication, scientists are therefore subject to intense scrutiny by their colleagues. | Peer Review |
| Peer review is one mechanism for ensuring honesty, objectivity, and quality in science. | Peer Review |
| Facts, Laws, and Theories | The most important product of scientific research is understanding how nature works-whether it be the nature of a pond to an ecologist or the nature of a liver cell to a physiologist. |
| A scientific fact is information that can be independently verified by any trained person—for example, the fact that an iron deficiency leads to -----. | anemia |
| A law of nature | is a generalization about the predictable ways in which matter and energy behave. |
| It is the result of ---- based on repeated, confirmed observations. | inductive reasoning |
| Some laws are expressed as concise verbal statements, such as the law of complementary base pairing | : In the double helix of DNA, a chemical base called adenine always pairs with one called thymine, and a base called guanine always pairs with cytosine. |
| Other laws are expressed as mathematical formulae, such as -----, used in respiratory physiology: V ∞ 1/P. | Boyle's law |
| Under specified conditions, the volume of a gas (V) is inversely proportional to its pressure (P)—that is, | V ∞ 1/P. |
| theories | is an explanatory statement or set of statements derived from facts, laws, and confirmed hypotheses. |
| theories | Some ---- have names, such as the cell theory, the fluid-mosaic theory of cell membranes, and the sliding filament theory of muscle contraction. |
| theories | Most, however, remain unnamed. The purpose of a ---- is not only to concisely summarize what we already know but, moreover, to suggest directions for further study and to help predict what the findings should be if the ---- is correct. |
| ---- and ---- mean something different in science than they do to most people. | law; theory |
| A ---- of nature, however, is a description; --- don't govern the universe-they describe it. | law |
| Laypeople | tend to use the word theory for what a scientist would call a hypothesis-for example, “I have a theory why my car won't start." |
| significant confusion | The difference in meaning causes ---- when it leads people to think that a scientific theory (such as the theory of evolution) is merely a guess or conjecture, instead of recognizing it as a summary of conclusions drawn from a large body of observed facts |
| The concepts of gravity and electrons are ---- , too, but this doesn't mean they're merely speculations | theories |
| The inductive method involves gathering numerous observations to form generalizations and predictions. | However, these truths remain flexible, ready to change if new observations contradict them. |
| Describe some sources of potential bias in biomedical research. What are some ways of minimizing such bias? | Potential biases in biomedical research can stem from funding sources, researcher expectations, and sample selection. Minimizing bias involves using randomized controlled trials, blinding, and diverse samples. |
| Describe some sources of potential bias in biomedical research. What are some ways of minimizing such bias? | Peer review and replication of studies further ensure reliability and objectivity, enhancing the credibility and accuracy of research findings. |
| Is there more information in an individual scientific fact or in a theory? Explain | A scientific theory encompasses more information than an individual fact, as it synthesizes numerous facts and observations into a comprehensive explanation. |
Created by:
Russells3709