modifications and updates for the April 18 course

factor_ana_testing_ml.Rmd

@@ -886,8 +886,8 @@ single cell data RNA--Seq data is commonly thought to contain more zeros
 than predicted by the NB distribution. As the additional zeros are believed
 to be due to technical factors such the efficiencies of reverse transcription,
 these additional zeros are also known as "dropouts".^[On the other hand,
-the NB model does not seem to be too bad for sc Data, see e.g. [Valentine Svensson 's](http://www.nxn.se/valent/2017/11/16/droplet-scrna-seq-is-not-zero-inflated) blog
-post on this matter.]
+the NB model does not seem to be too bad for sc Data, see e.g. [Valentine Svensson 's] blog
+posts on this matter [here](http://www.nxn.se/valent/2017/11/16/droplet-scrna-seq-is-not-zero-inflated) and [here](http://www.nxn.se/valent/2018/1/30/count-depth-variation-makes-poisson-scrna-seq-data-negative-binomial).]
 
 The proportion of zeros is modeled by \(\pi\) while \(mu\) are the counts.