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Alpha Criterion
The alpha () criterion is a predefined probability threshold—almost always set to 0.05 (or 5%)—that establishes how low a -value must be before researchers consider the sample result unlikely enough to reject the null hypothesis.
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Research Methods in Psychology - 4th American Edition @ KPU
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Factors Determining the p-value
Test Statistic
Misinterpretations of the p-value
Alpha (Level of Significance)
p-hacking
The 2015 Ban on Null Hypothesis Testing
Alpha Criterion
What does a p value represent in the context of psychological research?
If a psychology researcher calculates a p-value of 0.08, they will typically declare the experimental result to be statistically significant.
A social psychologist is analyzing data from four different studies. Based on the standard thresholds for statistical significance provided in the table, match each study's obtained p value with its correct interpretation.
Misinterpretation of the p Value
Determinants of the Value
A researcher obtains a value of and labels the result 'highly significant' (). According to standard significance thresholds, where and , this labeling is _____.
A cognitive psychologist conducts an experiment on learning styles and calculates a value of . Applying the standard threshold of significance () described in the text, the researcher should declare this result to be statistically significant.
Define what a value represents in the context of an experiment and state the standard threshold for declaring an experimental result to be statistically significant.
Reporting Effect Sizes in Null Hypothesis Significance Testing
Using the convention stated in this question for marking results with asterisks (a cut-off value itself counts as meeting it), match each label with the range of values it marks.
By a common convention in psychology, a result is declared statistically significant when . For a result exactly at this threshold (), results at least as extreme would occur, under the test's model (the null hypothesis plus the test's assumptions), time in how many?
By a common convention in psychology, a result is declared statistically significant when . For a result exactly at this threshold (), if the null hypothesis and the test's assumptions were true, results at least as extreme would occur 1 time in _____.
Arrange the following three values in ascending numerical order, from the smallest (1) to the largest (3).
A psychologist has values from four different studies. Arrange the values in ascending numerical order, from the smallest to the largest. (This orders the numbers only: values from different studies, each calculated under its own model, do not by themselves rank how strong the evidence is.)
A psychology student runs an analysis on their study's data and obtains a value of . Using the common convention of a significance level of (a result is significant when ), what conclusion should the student draw about their experimental result, and why?
Based on the definition of a value and a significance level of set in advance, explain in your own words what it means if, assuming the null hypothesis and the test's assumptions were true, a result at least as extreme as the researchers' would occur less than 1 time in 20, and what this does not establish.
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Which of the following best describes the alpha criterion in hypothesis testing?
In psychological research, a result with a p value of .03 would lead a researcher to reject the null hypothesis when the alpha criterion is set at .05, because the p value falls below the predefined threshold.
A psychology researcher is evaluating the results of four independent studies. Match each study's significance threshold (alpha) and obtained p value to the correct statistical decision.
A psychological researcher is evaluating how different alpha criteria affect the burden of proof required to reject a null hypothesis. Arrange these alpha values in order from the one that is the most stringent (requires the most extreme and unlikely sample result to reject the null) to the one that is the least stringent.
A researcher is developing a formal protocol for a new psychological study and must establish a rigorous decision-making framework. Arrange the following procedural steps in the correct sequence to construct a research plan that properly integrates the alpha () criterion.
The alpha () criterion in psychological research is a probability threshold that is established after data collection and analysis have occurred.
In psychological research, which statement best explains the role of the alpha () criterion as a decision-making threshold?
A professor presents four descriptions related to the alpha () criterion in null hypothesis testing. Match each description to the concept or outcome it correctly identifies.
A student claims: 'Since is the standard in psychology, a researcher never needs to justify using it—it is automatically the right choice.' A research methods instructor would consider this reasoning _____, because the alpha criterion, while conventionally set to .05, must be established deliberately before data collection as a reasoned decision about how low a value must be before rejecting the null hypothesis, not adopted blindly just because it is conventional.
A researcher obtains a value of .04 and rejects the null hypothesis using an alpha criterion of .05. A skeptic who evaluates this result as 'unconvincing' because it is not rare enough is essentially judging that the researcher should have used a more _____ alpha criterion, such as .01.
Define the alpha () criterion in the context of psychological research. What is its standard predefined threshold value, and how does this threshold guide a researcher's decision regarding the null hypothesis?
Based on the provided case, explain how the psychologist should use the alpha () criterion to interpret her value of .03. What does this mean for her decision regarding the null hypothesis, and why?
A research group is studying the impact of sleep deprivation on cognitive performance. They set their alpha () criterion to .05. Explain how they would apply this criterion if their statistical analysis yields a value of .08, and specify their final decision about the null hypothesis.