Descriptive statistics and ANOVA

73 Pages·2017·2.43 MB·English

by  Thomas Alexander Gerds

Basic statistics
Descriptive statistics and ANOVA
Thomas Alexander Gerds
DepartmentofBiostatistics,UniversityofCopenhagen
Contents
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Data are variable
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Statistical uncertainty
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Summary and display of data
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Confidence intervals
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ANOVA
Data are variable
A statistician is used to receive a value, such as
3.17 %,
together with an explanation, such as
"this is the expression of 1-B6.DBA-GTM in mouse 12".
The value from the next mouse in the list is 4.88% ...
The measurement is difficult
Data processing is done by humans
Two mice have different genes
They are exposed
...and treated differently
Decomposing variance
Variability of data is usually a composite of
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Measurement error, sampling scheme
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Random variation
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Genotype
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Exposure, life style, environment
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Treatment
Statistical conclusions can often be obtained by explaining the
sources of variation in the data.
Example 1
In the yeast experiment of Smith and Kruglyak (2008) 1 transcript
levels were profiled in 6 replicates of the same strain called ’RM’ in
glucose under controlled conditions.
1the article is available at http://biology.plosjournals.org