Regression 3 year data

#NARROW DOWN COVRIATES TO INCLUDE IN FINAL MODEL

load("Covariates.rda")
all<-all[,c(1,3:12)]
a<-read.csv("draft_ethnicity_brexit_03.csv")
test3<-merge(a,all,all.x=TRUE)
attach(test3)

RegModel.1 <- 
  lm(Pct_Leave.x~rate_nonUk+age_grp18_24+age_grp25_34+age_grp35_44+age_grp45_54+age_grp55_64+
  age_grp65_over+Area.Sq.Km+
 Mid.2016.Population+Pct_Turnout.x+Rejected_Ballots+
  People.per.Sq.Km,  data=test3)
   
 #STEPWISE SIMPLIFICATION
drop1(RegModel.1, test="F")

#At the 3 year level, drop1 proposed dropped variables are Age group 45-54 
RegModel.2<-update(RegModel.1,~.-age_grp45_54)
anova(RegModel.1,RegModel.2,test="Chi") #P=0.799

summary(RegModel.2)

#Significant: rate_nonUk, all age bands, Area.sq.km, change10, 
#Mid2016 Population, Pct_Turnout.x, change10,Mid.2016.Population,Pct_Turnout.x,Rejected_Ballots,People.per.Sq.Km

#EXPAND ETHNICITY (REPLACE rate_nonUk with ethnicity specific rates)
 
load("Brexit03Covariates.rda")
RegModel.5<-lm(formula = Pct_Leave.y ~ age_grp18_24 + age_grp25_34 + age_grp35_44 + 
    age_grp45_54 + age_grp55_64 + age_grp65_over + Area.Sq.Km + 
    Asian + Black + Mid.2016.Population + Other + Pct_Turnout.y + People.per.Sq.Km + 
    Rejected_Ballots + 
    White.British + White.Other, data = threeall)

drop1(RegModel.5, test="F")

RegModel.6<-update(RegModel.5,~.-age_grp45_54)
anova(RegModel.5,RegModel.6,test="Chi") #P=0.7564

RegModel.7<-update(RegModel.6,~.-Other)
anova(RegModel.6,RegModel.7,test="Chi") #P=0.659

drop1(RegModel.7, test="F")

RegModel.8<-update(RegModel.7,~.-Asian)
anova(RegModel.7,RegModel.8,test="Chi") #P=0.2106

RegModel.9<-update(RegModel.8,~.-age_grp25_34)
anova(RegModel.8,RegModel.9,test="Chi") #P=0.215

drop1(RegModel.9, test="F")

RegModel.10<-update(RegModel.9,~.-Black)
anova(RegModel.9,RegModel.10,test="Chi") #P=0.1933

RegModel.11<-update(RegModel.10,~.-White.Other)
anova(RegModel.10,RegModel.11,test="Chi") #P=0.0315 #Cannot be dropped

RegModel.12<-update(RegModel.10,~.-Mid.2016.Population)
anova(RegModel.10,RegModel.12,test="Chi") #P=0.06183 

drop1(RegModel.12, test="F")
summary(RegModel.12)