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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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Test Statistic
Misinterpretations of the p-value
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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.
A psychologist is comparing findings across four different research studies. Based on the definition of a p value and the significance thresholds provided in the table, arrange these findings in order from the outcome LEAST likely to have occurred by chance to the outcome MOST likely to have occurred by chance.
According to the standard threshold of significance () in psychology, a research result is typically declared significant if the probability of it occurring purely by chance is less than in how many?
Misinterpretation of the p Value
Determinants of the Value
Based on the significance thresholds provided in the table and the definition of a value, match each statistical label with the correct description of its probability occurring purely by chance.
A researcher obtains a value of 0.02 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 0.04. Applying the standard threshold of significance () described in the text, the researcher should declare this result to be statistically significant.
According to the standard threshold of significance (), a psychological research result is typically declared significant if the probability of the outcome occurring purely by chance is less than 1 in _____.
Evaluate the following three experimental results and arrange them in order from the outcome representing the lowest probability of occurring purely by chance (1) to the outcome representing the highest probability of occurring purely by chance (3).
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.
Based on the standard definition of a value and its typical threshold, explain in your own words what it means if the researchers determined the probability of their outcome occurring purely by chance was less than 1 in 20.
A psychology student runs an analysis on their study's data and discovers the probability of their results occurring purely by chance is 0.03. Applying the standard threshold of significance, what conclusion should the student draw about their experimental result, and why?
Reporting Effect Sizes in Null Hypothesis Significance Testing
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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.