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Keywords: Probability and p-values; significance as a threshold of p-values; deriving probability distributions from simulation and interpreting in terms of significance. | |||||||
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Deliverables: Time management: Before you begin, estimate how long it will take you to complete this unit. Then, record in your course journal: the number of hours you estimated, the number of hours you worked on the unit, and the amount of time that passed between start and completion of this unit. Journal: Document your progress in your Course Journal. Some tasks may ask you to include specific items in your journal. Don’t overlook these. Insights: If you find something particularly noteworthy about this unit, make a note in your insights! page. |
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Evaluation: NA: This unit is not evaluated for course marks. |
The probability of an event is the chance of it occurring, but how do we relate that to the question whether an observation is significant? In this context we talk about p-values and the meaning of a p-value is not the same as the probability of an observation. The p-value of an observation is the probability that - assuming a null hypothesis is true - an event as extreme or more extreme is observed. This unit contains R code to study this concept.
Task…
ABC-units
R project. If you
have loaded it before, choose File ▸ Recent
projects ▸ ABC-Units. If you have not loaded
it before, follow the instructions in the RPR-Introduction
unit.init()
if requested.FND-STA-Significance.R
and follow the
instructions.
Note: take care that you understand all of the code in the script. Evaluation in this course is cumulative and you may be asked to explain any part of code.
Task…
Examine the papers below that introduce difficulties with P-values and statistical significance. Rephrase the issues in your own words to make sure that you understand what the discussion is about.
Baker,
Monya. (2016). “Statisticians issue warning over misuse of P
values”. Nature 531(7593):151 .
[PMID: 26961635]
[DOI: 10.1038/nature.2016.19503]
Nieuwenhuis,
Sander, Birte U Forstmann, and Eric-Jan Wagenmakers. (2011).
“Erroneous analyses of interactions in neuroscience: a problem of
significance”. Nature Neuroscience
14(9):1105–7 .
[PMID: 21878926]
[DOI: 10.1038/nn.2886]
J, Murdoch,
D, Tsai, Yu-Ling, and Adcock, James. (2008). “P-Values are Random
Variables”. The American Statistician Taylor & Francis,
Alexandria, VA. 62(3):242–245 .
[DOI: 10.1198/000313008X332421]
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