Scientific Method
The basic elements of scientific thinking include:
Make observations. Formulate a hypothesis. Devise a testable prediction. Conduct a critical experiment. Draw conclusions and make revisions.
Variables
factors that can change in an experiment
blind experimental design
the experimental subjects do not know which treatment (if any) they are receiving
A critical experiment is one that makes it possible to decisively determine whether a particular hypothesis is correct.
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A key element of scientific thinking is that it is empirical. Empirical knowledge is based on experience and observations that are rational, testable, and repeatable. Another important element of scientific thinking is that it is self-correcting.
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Based on the results of experimental tests, we can revise a hypothesis and explain the observable world with increasing accuracy. A great strength of scientific thinking, therefore, is that it helps us understand when we should change our minds.
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Biases can influence our behavior, including our collection and interpretation of data. With careful controls, it is possible to reduce the impact of biases.
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Both types of hypothesis are equally valid, but a null hypothesis is typically easier to disprove. Any new observation that contradicts a null hypothesis can be sufficient for the researcher to reject it and conclude that an alternative hypothesis must be considered.
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For a hypothesis to be useful, it must generate a testable prediction
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One of the most common functions of visual displays of information is to present the relationship between two variables, such as in a graph. As we saw in Section 1.10, an independent variable can be changed by the experimenter as required, while a dependent variable is one whose response is created by the process being observed and depends on the independent variable. The dependent variable is generally represented on the y-axis and is expected to change in response to a change in the independent variable, represented on the x-axis.
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Scientific theories do not represent casual guesses about the natural world. Rather, they are hypotheses—proposed explanations for natural phenomena—that have been so strongly and persuasively supported by empirical observation that the scientific community views them as very unlikely to be altered by new evidence.
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Scientific thinking begins by making observations about the world, noting apparent patterns or cause-and-effect relationships.
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To draw clear conclusions from experiments, it is essential to hold constant the variables we are not interested in. Control and experimental groups should differ only with respect to the treatment. Biases can influence our behavior, including our collection and interpretation of data. With careful controls, we can reduce the impact of biases.
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Visual displays of data, which condense large amounts of information, can aid in the presentation and exploration of the data. The effectiveness of such displays is influenced by the precision and clarity of the presentation, and can be reduced by ambiguity, biases, hidden assumptions, and other issues that reduce a viewer's confidence in the underlying truth of the presented results.
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Whether making a point, illustrating an idea, or facilitating the testing of a hypothesis, visual displays of data condense large amounts of information into a more easily digested form.
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he use of "randomized, controlled, double-blind" experimental design can be thought of as an attempt to imagine all the possible ways that someone might criticize an experiment and to design the experiment so that the results cannot be explained by anything other than the effect of the treatment.
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it is essential to hold constant all those variables we are not interested in. Ideally, control and experimental groups should differ only with respect to the treatment of interest. Differences in outcomes between the groups can then be attributed to the treatment.
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To be most useful, a hypothesis must accomplish two things.
1. It must establish an alternative explanation for a phenomenon. That is, it must be clear that if the proposed explanation is not supported by evidence or further observations, a different hypothesis is a more likely explanation. 2. It must generate testable predictions .This characteristic is important because we can evaluate the validity of a hypothesis only by putting it to the test.
Hypothesis
A hypothesis is a proposed explanation for a phenomenon. A useful hypothesis leads to testable predictions.
scientific theory
A scientific theory is an explanatory hypothesis for natural phenomena that is exceptionally well-supported by empirical data. A scientific theory can be thought of as a hypothesis that has withstood the test of time and is unlikely to be altered by any new evidence. Like a hypothesis, a scientific theory generates predictions and is testable; but because it has already been repeatedly tested and no experimental results have contradicted it, a scientific theory is viewed by the scientific community with nearly the same confidence as a fact.
Hypothesis
A testable prediction, often implied by a theory
experimental group
In an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable.
control group
In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.
Key Points of scientific method
Scientific thinking is an empirical process that incorporates making observations, articulating hypotheses, generating predictions, designing experimental tests, and drawing conclusions. It is a flexible, adaptable, and efficient process, and it can tell us when we must change our beliefs. Scientific thinking begins by making observations about the world, noting apparent patterns or cause-and-effect relationships. A hypothesis is a proposed explanation for an observed phenomenon. For a hypothesis to be useful, it must generate a testable prediction. A critical experiment is one that enables us to decisively determine whether a particular hypothesis is correct. Based on the results of experimental tests, we can revise a hypothesis and explain the observable world with increasing accuracy. Scientific theories are hypotheses that have been so persuasively supported by empirical observations that they are unlikely to be altered by new evidence.
What's the most important outcome of scientific thinking?
Scientific thinking tells us when to change our minds about the natural world.
independent variable
The experimental factor that is manipulated; the variable whose effect is being studied.
dependent variable
The outcome factor; the variable that may change in response to manipulations of the independent variable.
placebo
a fake drug used in the testing of medication
critical experiment
an experiment that makes it possible to decisively determine whether a particular hypothesis is correct
Emperical
based on observation or experiment and not on theory; Describes knowledge that is based on experience and observations that are rational, testable, and repeatable.
treatment group
group being studied that receives a treatment
Scientific Method
highly flexible process that can be used to explore a wide variety of thoughts, events, or phenomena, not only in science but in other areas as well
Replication
repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances
null hypothesis
the hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error. Can be proved wrong.
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the process doesn't necessarily continue linearly through five non-overlapping steps until it is concluded Sometimes, initial observations lead to more than one hypothesis and several testable predictions and experiments
