* Correlation example revisited. Original oberveations

cd "M:\Ntnu\KLMED8008\Dag1" // Use your own directory!
use x67, clear
graph twoway (scatter x7 x6), yline(30.75) xline(35.1) 
gen D = x7 - x6 // 
ttest D ==0 //

* Now using the "shuffeled" x7 instead
use x67s, clear
gen D = x7s - x6 //
graph twoway (scatter x7s x6), yline(30.75) xline(35.1) //
ttest D ==0 //

* Taking baseline value into consideration in an RCT
cd "M:\Ntnu\KLMED8008\Dag2" // Use your own directory!

use Vickers, replace
describe       // slide 5
list in 1/8    // slide 5
list in 28/36  // slide 5

table group, c(mean pre mean post) row col // slide 7
ttest post, by (group) // slide 7

twoway (scatter post pre if group == 0, ms(oh)) (scatter post pre if group == 1, ///
ms(+)), ytitle (Post treatment score) xtitle /// slide 8
(Pre treatment score) legend (label(1 Placebo) label(2 Acupuncture) label ///
( 3 Placebo) label(4 Acupuncture) )

table group, c(mean pre mean post) // slide 9
ttest pre, by (group) //slide 9

table group, c(mean pre mean post) // slide 10
ttest d, by(group)  // slide 10

table group, c(mean pre mean post) // slide 11

regress post pre i.group // slide 11

* with interaction (i.e. let the slope varyu between groups also)
regress post c.pre##i.group // 
margins i.group, at(pre = 57) 
lincom 1.group + 53.9*pre + 53.9*1.group#c.pre

regress d pre i.group
margins i.group, at(pre = 57) 

Adjusted predictions                              Number of obs   =         52
Model VCE    : OLS

Expression   : Linear prediction, predict()
at           : pre             =          57

------------------------------------------------------------------------------
             |            Delta-method
             |     Margin   Std. Err.      z    P>|z|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
       group |
          0  |   7.479549   2.925014     2.56   0.011     1.746627    13.21247
          1  |   20.18527   3.045477     6.63   0.000     14.21624    26.15429
------------------------------------------------------------------------------


twoway (scatter post pre if group == 0, ms(oh)) (scatter post pre if group == 1, ///
ms(+)) (function y=23.9+ 0.71*x, range (pre) lpatt(dash)) (function y=23.9 /// slide 12
+12.7+ 0.71*x, range (pre) lpatt(solid)), ytitle (Post treatment score) xtitle ///
(Pre treatment score) legend (label(1 Placebo) label(2 Acupuncture) label ///
( 3 Placebo) label(4 Acupuncture) )

pwcorr pre post, sig // slide 15

sampsi 55 60, sd(15) pre(1) r01(0.55) // slide 16 and 17


* ANOVA
use lwiner, clear
table drug, c(mean score sd score) // slide 20
list //slide 20, right

anova score drug // slide 22
margins drug // slide 22
graph box score, over (drug) // slide 23 (and slide 30)
pwcompare drug, bonferroni effects // slide 24

use wwiner, clear // slide 27
list // slide 24

* We need the 'long' format again
use winer, clear // naiv anova-analyse
anova score person drug, repeated(drug) // slide 28
margins drug // slide 29
pwcompare drug, bonferroni effects // slide 31

findit Friedman // package snp2_1 from http://www.stata-journal.com/software/sj5-2
use wwiner, clear // 
list
friedman score* // score* means score_1 score_2 score_3 score_4
signrank score_1 = score_2 // slide 35

use wwiner, clear // 
signrank score_2 = score_3 // slide 36