Presenting R

Here is a short presentation I made for fellow students at work.

It is generally at a beginner’s level or for people having trouble transitioning to R.

and if you want to see the video presentation you can see it from here on UTK’s lecture capture mechanism

Title: R Help Session
Speaker: A. Ohri
Desription: Session for R Beginners
URL: http://vcweb.bus.utk.edu/20090911-103113-cap403/

In addition, here is a link for the handout:

https://docs.google.com/present/edit?id=0AdYMMvghK2ytZGN2c3MzNThfODA2ZzY4N2I5bno&hl=en&invite=CKvforMH

ROC Curve

ROC Curve is a nice modeling concept to know as it will used practically in nearly all models

irrespective of spoefic technique and irrespective of statistical software.

We use the Wikipedia for referring to easy to implement statistics rather than crusty

thick books which seem prohibitely dense and opaque to outsiders

-This is how you define the ROC Curve.

actual value
p n total
prediction
outcome
p’ True
Positive
False
Positive
P’
n’ False
Negative
True
Negative
N’
total P N

true positive (TP)

eqv. with hit
true negative (TN)
eqv. with correct rejection
false positive (FP)
eqv. with false alarm, Type I error
false negative (FN)
eqv. with miss, Type II error
true positive rate (TPR)
eqv. with hit rate, recall, sensitivity
TPR = TP / P = TP / (TP + FN)
false positive rate (FPR)
eqv. with false alarm rate, fall-out
FPR = FP / N = FP / (FP + TN)
accuracy (ACC)
ACC = (TP + TN) / (P + N)
specificity (SPC)
SPC = TN / (FP + TN) = 1 ? FPR
positive predictive value (PPV)
eqv. with precision
PPV = TP / (TP + FP)

Here is a good java enabled page to calculate the ROC Curve.

http://www.rad.jhmi.edu/jeng/javarad/roc/JROCFITi.html

And in case any one asks, ROC stands for Receiver Operating Characteristic. ……

Learning R Easily :Two GUI’s

Both Rattle and R Commander are very good GUI’s (graphical user interface) for R, and considerably easier for a beginner than the command line console ( but I am more partial to RCmdr for normal statistical analysis while Rattle seemed to have better Data Mining Interfaces and functionality).

Here is a snapshot for both of them.

Installing them both is a breeze as you set a CRAN Mirror from Normal R Console and install package from list of package names . R has hundreds of packages (All free!!) and you can thus install specific packages to your need and usage.The software R automatically downloads and installs them.

rcommdr.GIF..

Installling both these GUI will ensure you cut down the time to learn commands as you can first click and try and learn the syntax that is auto generated side by side.

rattle.GIF

Learning R Easily :Two GUI's

Both Rattle and R Commander are very good GUI’s (graphical user interface) for R, and considerably easier for a beginner than the command line console ( but I am more partial to RCmdr for normal statistical analysis while Rattle seemed to have better Data Mining Interfaces and functionality).

Here is a snapshot for both of them.

Installing them both is a breeze as you set a CRAN Mirror from Normal R Console and install package from list of package names . R has hundreds of packages (All free!!) and you can thus install specific packages to your need and usage.The software R automatically downloads and installs them.

rcommdr.GIF..

Installling both these GUI will ensure you cut down the time to learn commands as you can first click and try and learn the syntax that is auto generated side by side.

rattle.GIF