version 9.2

log using C:\Teaching\IGP\log\anova.log, replace

* Chapter 7 Analysis of variance
* modified on Feb. 03, 2007 by Leena Choi

use "C:\Teaching\IGP\data\hemoANOVA.dta", clear

* make dotplot to display the data by the type of sickle cell disease
dotplot hemo, over(type) center mean

* put informative label
label variable hemo "Hemoglobin (g/dL)"
label variable type "Type of sickle cell disease"
label define typelab 1 "Hb SS" 2 "Hb S/beta" 3 "Hb SC"
label values type typelab

* see the difference between the previous dotplot and the new dotplot after labelling
dotplot hemo, over(type) center mean

*draw box plot
graph box hemo, over(type)

* calculate the overall 95% confidence interval for hemoglobin
ci hemo

* calculate 95% confidence interval for hemoglobin by type
sort type
by type: ci hemo

* perform one-way anova
oneway hemo type

* calculate F-value using the MS
display 49.9446532/.998907972

* calculate F-value using the SS
display (99.8893064/2)/(37.9585029/38)

* perform one-way anova with summary table, and mutiple comparison tests using bonferroni procedure
oneway hemo type, tabulate bonferroni

log close