corrected a typo ...
Update README.md
Create crossvalidation.md
Create df.md
Update p-value.md
Update p-value.md
Update R20-DataStructures.md
small changes
Update R20-DataStructures.md
Update stats03-summaryStatistisc.md
Update R20-DataStructures.md
Update R20-DataStructures.md
Update R20-DataStructures.md
Update R20-DataStructures.md
Merge branch 'master' into gh-pages

Conflicts:
	README.md