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Misinterpretation of the p Value
The most common misinterpretation of the value is mistakenly believing it represents the probability that the null hypothesis is true (i.e., the probability that the result occurred by chance). In reality, the value calculates the probability of obtaining the specific sample data assuming the null hypothesis is already true.
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Research Methods in Psychology - 4th American Edition @ KPU
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Don't make such black and white interpretations
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 describes the most common misinterpretation of the p value in psychological research?
A researcher investigating the relationship between violent video games and aggression finds a statistically significant result with a value of .04. The researcher states, 'There is a 4% probability that the null hypothesis is true and that video games have no effect on aggression.' This statement represents a correct interpretation of the value.
A psychologist studying the effects of mindfulness on stress obtains a result with a value of .03. To avoid the most common misinterpretation of this value, the researcher must correctly analyze the logical structure of the statistical test. Arrange the following steps in the correct order, starting with the foundational assumption of the test.
The value represents the probability that the null hypothesis is true.
A researcher conducts a study comparing two therapy techniques for reducing test anxiety and obtains a p value of .02. She states: 'There is only a 2% chance that the null hypothesis is true.' This is a correct interpretation of the p value.
Which of the following represents the most common misinterpretation of a p value?
A researcher testing a new memory-enhancement exercise finds a value of .05. Match each statement regarding this result to its appropriate categorization.
In psychological research, the value is frequently misunderstood. Arrange the following steps to represent the correct logical process of determining a value, ending with the statement that describes the most common logical error made during its interpretation.
You are designing an automated peer-review system intended to help students identify and correct errors in their lab reports. To address the most common misinterpretation of the value, you need to program the system to replace flawed conclusions with technically accurate ones. If a student concludes that their result () means there is a '4% chance that the null hypothesis is true,' which of the following replacements should your system suggest to correctly construct the meaning
A researcher claims that a result with a value of .05 means there is a 5% probability that the null hypothesis is true. A methodologist evaluating this claim would point out that the value actually represents the probability of the _____, given the assumption that the null hypothesis is true.
A researcher conducts a study on social loafing and obtains a result with . In their discussion, they state: 'There is only a 3% probability that our results were produced by chance.' To evaluate the logical flaw in this conclusion, a student must recognize that the researcher has mistakenly equated the value with the probability of the _____ being true, rather than the probability of the data given that it is true.
Match each claim about a result where to its correct label.
A student researcher writes the following sentence in their lab report discussion section: 'Because our study yielded a value of .04, there is a 4% probability that the null hypothesis is true.' Explain why this statement is incorrect and rewrite the interpretation correctly based on the true definition of a value.
Diagnose the methodological error in Dr. Smith's statement. Analyze how the elements of their quote reflect the most common misinterpretation of the value, and explain what the 1% actually calculates in the context of their research data.
A peer reviewer rejects a manuscript because the authors state, 'Our value of .03 proves there is a 3% chance the null hypothesis is true.' Evaluate the validity of the peer reviewer's reason for rejection in one to three sentences, using the correct definition of the value to justify your evaluation.