The Future of Statistical Software Proceedings of a Forum (1991) / Chapter Skim
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Guidance for One-Way ANOVA
Guidance for One-Way ANOVA
Pages 43-50
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From page 43... ...
The first goal of guidance is to permit the occasional, infrequent user whose main business is not statistical data analysis (such as a scientist or engineer) to achieve the benefits of using basic statistical procedures.
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From page 44... ...
Yet software is much better used if the user has to think about a database of random variables and relationships between those variables. Forcing users to do that is, in a sense, a disadvantage of software, but also an ultimate advantage for users; if people understand and think about random variables, it will greatly help them to think about statistical issues in the right manner.
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From page 45... ...
There should be some automatic screening or adaptive fitting procedure as guidance, in which the software itself does the kinds of things that most statisticians would recommend. This includes such things as recognizing horribly skewed distributions, or recognizing when a response variable only takes two or three values, examining whether or not there are differences between the spreads in each group.
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From page 46... ...
One can give descriptions of the model and/or data, explore the residuals, explain the ANOVA table, produce confidence intervals -- to understand esoterica such as the simultaneous versus the non-simultaneous approach to estimating confidence inteIvals-and make confidence intervals for fitted values. Again, software can help with that task.
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From page 47... ...
Aside from the issue of data dependence interpretations, there are trickier issues, such as what one means by a simultaneous confidence interval. Suppose the following standard sentence is produced describing how to interpret a particular confidence interval: The true mean of GAIN where DIET = liquid, minus the true mean where DIET = solid, is approximately 10.9, and is between -14.7 and 36.7 using simultaneous 95% confidence intervals.
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From page 48... ...
Guidance Regarding Tacit Technical Assumptions T now want to talk a bit more technically about some problems related to giving guidance. How can one overcome what are major pitfalls, violations of the major statistical assumptions made in the statistical model, in the one-way ANOVA layout?
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From page 49... ...
Regarding testing versus estimation, if one has huge sample sizes and one variance is proved significantly to be 20 percent bigger than another variance, that is not at all relevant to the question of what kind of procedure one should use for one-way ANOVA. The infrequent and non-statistician user does not want to be concerned with all these technicalities.
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From page 50... ...
Perhaps a manipulation metaphor can make the goals of statistics more transparent and concrete, as well as the uncertainty measures produced by a statistical program. This is going to produce more for the guidance and overall understanding than boilerplate dialogues that attempt to mimic the discussion that an expert statistician might have with a client.
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