library("Zelig")
## Loading required package: MASS
## Loading required package: boot
## ## 
## ##  Zelig (Version 3.5.3, built: 2011-11-29)
## ##  Please refer to http://gking.harvard.edu/zelig for full
## ##  documentation or help.zelig() for help with commands and
## ##  models supported by Zelig.
## ##
## 
## ##  Zelig project citations:
## ##    Kosuke Imai, Gary King, and Olivia Lau. (2009).
## ##    ``Zelig: Everyone's Statistical Software,''
## ##    http://gking.harvard.edu/zelig.
## ##  and
## ##    Kosuke Imai, Gary King, and Olivia Lau. (2008).
## ##    ``Toward A Common Framework for Statistical Analysis
## ##    and Development,'' Journal of Computational and
## ##    Graphical Statistics, Vol. 17, No. 4 (December)
## ##    pp. 892-913. 
## 
## ##  To cite individual Zelig models, please use the citation format printed with
## ##  each model run and in the documentation.
## ##
library("DescTools")
library("dplyr")
## Warning: package 'dplyr' was built under R version 3.1.3
## 
## Attaching package: 'dplyr'
## 
## The following object is masked from 'package:MASS':
## 
##     select
## 
## The following object is masked from 'package:stats':
## 
##     filter
## 
## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union
library("stargazer")
## 
## Please cite as: 
## 
##  Hlavac, Marek (2014). stargazer: LaTeX code and ASCII text for well-formatted regression and summary statistics tables.
##  R package version 5.1. http://CRAN.R-project.org/package=stargazer
library("readstata13")
## Warning: package 'readstata13' was built under R version 3.1.3
library("foreign")
library("car")
## 
## Attaching package: 'car'
## 
## The following object is masked from 'package:DescTools':
## 
##     Recode
## 
## The following object is masked from 'package:boot':
## 
##     logit
library("npmlreg")
## Warning: package 'npmlreg' was built under R version 3.1.3
library("texreg")
## Warning: package 'texreg' was built under R version 3.1.3
## Version:  1.34
## Date:     2014-10-31
## Author:   Philip Leifeld (University of Konstanz)
## 
## Please cite the JSS article in your publications -- see citation("texreg").
library("lme4")
## Loading required package: Matrix
## 
## Attaching package: 'Matrix'
## 
## The following object is masked from 'package:npmlreg':
## 
##     expand
## 
## Loading required package: Rcpp
library("magrittr")
## Warning: package 'magrittr' was built under R version 3.1.3
## 
## Attaching package: 'magrittr'
## 
## The following object is masked from 'package:texreg':
## 
##     extract
data(irlsuicide)
str(irlsuicide)
## 'data.frame':    104 obs. of  8 variables:
##  $ Region  : Factor w/ 13 levels "Cork ","Dublin ",..: 1 1 1 1 1 1 1 1 2 2 ...
##  $ ID      : Factor w/ 13 levels "1","2","3","4",..: 1 1 1 1 1 1 1 1 2 2 ...
##  $ pop     : int  31923 31907 8517 8127 13527 12965 11958 8299 117575 114626 ...
##  $ death   : int  6 52 8 37 17 33 14 22 33 114 ...
##  $ sex     : Factor w/ 2 levels "0","1": 1 2 1 2 1 2 1 2 1 2 ...
##  $ age     : Factor w/ 4 levels "1","2","3","4": 1 1 2 2 3 3 4 4 1 1 ...
##  $ smr     : num  97.7 144 181.7 193.4 182.4 ...
##  $ expected: num  6.14 36.11 4.4 19.13 9.32 ...
summary(irlsuicide)
##         Region         ID          pop             death        sex   
##  Cork      : 8   1      : 8   Min.   :  2434   Min.   :  1.00   0:52  
##  Dublin    : 8   2      : 8   1st Qu.: 13192   1st Qu.:  9.00   1:52  
##  EHB - Dub.: 8   3      : 8   Median : 23878   Median : 21.00         
##  Galway    : 8   4      : 8   Mean   : 34512   Mean   : 36.77         
##  Lim.      : 8   5      : 8   3rd Qu.: 46879   3rd Qu.: 52.75         
##  Mid HB    : 8   6      : 8   Max.   :210422   Max.   :198.00         
##  (Other)   :56   (Other):56                                           
##  age         smr            expected      
##  1:26   Min.   : 27.20   Min.   :  1.529  
##  2:26   1st Qu.: 90.08   1st Qu.:  9.296  
##  3:26   Median :109.40   Median : 17.983  
##  4:26   Mean   :112.88   Mean   : 33.647  
##         3rd Qu.:134.60   3rd Qu.: 45.291  
##         Max.   :252.30   Max.   :238.267  
## 

Complete Pooling Model

cpooling <- zelig(death ~ Region + sex, data = irlsuicide, model = "normal")
## How to cite this model in Zelig:
## Kosuke Imai, Gary King, and Oliva Lau. 2007. "normal: Normal Regression for Continuous Dependent Variables" in Kosuke Imai, Gary King, and Olivia Lau, "Zelig: Everyone's Statistical Software," http://gking.harvard.edu/zelig
stargazer(cpooling, type = "text", single.row = T)
## 
## =============================================
##                       Dependent variable:    
##                   ---------------------------
##                              death           
## ---------------------------------------------
## RegionDublin          37.000*** (12.339)     
## RegionEHB - Dub.      51.750*** (12.339)     
## RegionGalway           -17.250 (12.339)      
## RegionLim.             -15.250 (12.339)      
## RegionMid HB            3.000 (12.339)       
## RegionMWHB - Lim.       14.500 (12.339)      
## RegionNEHB              17.750 (12.339)      
## RegionNWHB              4.625 (12.339)       
## RegionSEHB - Wat.     34.125*** (12.339)     
## RegionSHB - Cork      40.125*** (12.339)     
## RegionWaterf.          -19.125 (12.339)      
## RegionWHB - Gal.        19.625 (12.339)      
## sex1                   45.000*** (4.840)     
## Constant                 1.125 (9.055)       
## ---------------------------------------------
## Observations                  104            
## Log Likelihood             -474.470          
## Akaike Inf. Crit.           976.939          
## =============================================
## Note:             *p<0.1; **p<0.05; ***p<0.01
cpooling1 <- zelig(death ~ Region + sex + Region:sex, data = irlsuicide, model = "normal")
## How to cite this model in Zelig:
## Kosuke Imai, Gary King, and Oliva Lau. 2007. "normal: Normal Regression for Continuous Dependent Variables" in Kosuke Imai, Gary King, and Olivia Lau, "Zelig: Everyone's Statistical Software," http://gking.harvard.edu/zelig
stargazer(cpooling1, type = "text", single.row = T)
## 
## ==================================================
##                            Dependent variable:    
##                        ---------------------------
##                                   death           
## --------------------------------------------------
## RegionDublin                 20.500 (15.280)      
## RegionEHB - Dub.             20.500 (15.280)      
## RegionGalway                 -8.750 (15.280)      
## RegionLim.                   -8.500 (15.280)      
## RegionMid HB                 -2.250 (15.280)      
## RegionMWHB - Lim.            2.250 (15.280)       
## RegionNEHB                   2.500 (15.280)       
## RegionNWHB                   -2.000 (15.280)      
## RegionSEHB - Wat.            8.000 (15.280)       
## RegionSHB - Cork             13.000 (15.280)      
## RegionWaterf.                -8.750 (15.280)      
## RegionWHB - Gal.             2.750 (15.280)       
## sex1                         24.750 (15.280)      
## RegionDublin :sex1           33.000 (21.610)      
## RegionEHB - Dub.:sex1      62.500*** (21.610)     
## RegionGalway :sex1          -17.000 (21.610)      
## RegionLim. :sex1            -13.500 (21.610)      
## RegionMid HB:sex1            10.500 (21.610)      
## RegionMWHB - Lim.:sex1       24.500 (21.610)      
## RegionNEHB:sex1              30.500 (21.610)      
## RegionNWHB:sex1              13.250 (21.610)      
## RegionSEHB - Wat.:sex1      52.250** (21.610)     
## RegionSHB - Cork:sex1       54.250** (21.610)     
## RegionWaterf.:sex1          -20.750 (21.610)      
## RegionWHB - Gal.:sex1        33.750 (21.610)      
## Constant                     11.250 (10.805)      
## --------------------------------------------------
## Observations                       104            
## Log Likelihood                  -453.217          
## Akaike Inf. Crit.                958.434          
## ==================================================
## Note:                  *p<0.1; **p<0.05; ***p<0.01

The first complete pooling model tells us that there is a higher rate of female suicides in EHB-Dublin (p=.01), SEHB- Wat (p=.01), SHB-Cork (p=.01), and Dublin (p=.01). The second complete pooling model takes into account the interaction between gender and geographic region. The results tell us that there is a higher rate of suicide in women in EHB-Dublin (p=.01), SEHB-Wat (p=.05), and SHB-Cork (p=.05).

No-pooling Model

dcoef <- irlsuicide %>% 
    group_by(Region) %>% 
    do(mod = lm(death ~ sex, data = .))
coef <- dcoef %>% do(data.frame(sexc = coef(.$mod)[2]))
hist(coef$sexc)

coef <- data.frame(coef)
Desc(coef)
## 
## -------------------------------------------------------------------------
## 'data.frame':    13 obs. of  1 variable:
##  1 $ sexc: num  24.75 57.75 87.25 7.75 11.25 ...
## 
## ------------------------------------------------------------------------- 
## 1 - sexc (numeric)
## 
##   length      n    NAs unique     0s   mean meanSE
##       13     13      0    = n      0     45  7.677
## 
##      .05    .10    .25 median    .75    .90    .95
##    6.250  8.450 24.750 49.250 58.500 78.600 82.300
## 
##      rng     sd  vcoef    mad    IQR   skew   kurt
##   83.250 27.681  0.615 36.324 33.750 -0.056 -1.445
##  
## lowest : 4, 7.75, 11.25, 24.75, 35.25
## highest: 57.75, 58.5, 77, 79, 87.25
## 
## Shapiro-Wilks normality test  p.value : 0.55554

*Multi-level Models

m1_lme <- lmer(death ~ sex + (1|Region), data = irlsuicide)
summary(m1_lme)
## Linear mixed model fit by REML ['lmerMod']
## Formula: death ~ sex + (1 | Region)
##    Data: irlsuicide
## 
## REML criterion at convergence: 974.8
## 
## Scaled residuals: 
##     Min      1Q  Median      3Q     Max 
## -2.3654 -0.6604 -0.0931  0.5213  4.2800 
## 
## Random effects:
##  Groups   Name        Variance Std.Dev.
##  Region   (Intercept) 458.2    21.41   
##  Residual             609.0    24.68   
## Number of obs: 104, groups:  Region, 13
## 
## Fixed effects:
##             Estimate Std. Error t value
## (Intercept)   14.269      6.853   2.082
## sex1          45.000      4.840   9.298
## 
## Correlation of Fixed Effects:
##      (Intr)
## sex1 -0.353
m2_lme <- lmer(death ~ sex + (sex|Region), data = irlsuicide)
summary(m2_lme)
## Linear mixed model fit by REML ['lmerMod']
## Formula: death ~ sex + (sex | Region)
##    Data: irlsuicide
## 
## REML criterion at convergence: 943.1
## 
## Scaled residuals: 
##     Min      1Q  Median      3Q     Max 
## -4.0032 -0.2889 -0.0697  0.2623  4.0805 
## 
## Random effects:
##  Groups   Name        Variance Std.Dev. Corr
##  Region   (Intercept)  82.27    9.07        
##           sex1        693.73   26.34    1.00
##  Residual             411.59   20.29        
## Number of obs: 104, groups:  Region, 13
## 
## Fixed effects:
##             Estimate Std. Error t value
## (Intercept)   14.269      3.774   3.781
## sex1          45.000      8.318   5.410
## 
## Correlation of Fixed Effects:
##      (Intr)
## sex1 0.333
stargazer(cpooling, cpooling1, m1_lme, m2_lme, type = "text")
## 
## ==============================================================
##                                  Dependent variable:          
##                        ---------------------------------------
##                                         death                 
##                              normal              linear       
##                                               mixed-effects   
##                           (1)       (2)       (3)       (4)   
## --------------------------------------------------------------
## RegionDublin           37.000***  20.500                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionEHB - Dub.       51.750***  20.500                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionGalway            -17.250   -8.750                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionLim.              -15.250   -8.500                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionMid HB             3.000    -2.250                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionMWHB - Lim.       14.500     2.250                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionNEHB              17.750     2.500                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionNWHB               4.625    -2.000                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionSEHB - Wat.      34.125***   8.000                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionSHB - Cork       40.125***  13.000                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionWaterf.           -19.125   -8.750                      
##                        (12.339)  (15.280)                     
##                                                               
## RegionWHB - Gal.        19.625     2.750                      
##                        (12.339)  (15.280)                     
##                                                               
## sex1                   45.000***  24.750   45.000*** 45.000***
##                         (4.840)  (15.280)   (4.840)   (8.318) 
##                                                               
## RegionDublin :sex1                33.000                      
##                                  (21.610)                     
##                                                               
## RegionEHB - Dub.:sex1            62.500***                    
##                                  (21.610)                     
##                                                               
## RegionGalway :sex1                -17.000                     
##                                  (21.610)                     
##                                                               
## RegionLim. :sex1                  -13.500                     
##                                  (21.610)                     
##                                                               
## RegionMid HB:sex1                 10.500                      
##                                  (21.610)                     
##                                                               
## RegionMWHB - Lim.:sex1            24.500                      
##                                  (21.610)                     
##                                                               
## RegionNEHB:sex1                   30.500                      
##                                  (21.610)                     
##                                                               
## RegionNWHB:sex1                   13.250                      
##                                  (21.610)                     
##                                                               
## RegionSEHB - Wat.:sex1           52.250**                     
##                                  (21.610)                     
##                                                               
## RegionSHB - Cork:sex1            54.250**                     
##                                  (21.610)                     
##                                                               
## RegionWaterf.:sex1                -20.750                     
##                                  (21.610)                     
##                                                               
## RegionWHB - Gal.:sex1             33.750                      
##                                  (21.610)                     
##                                                               
## Constant                 1.125    11.250   14.269**  14.269***
##                         (9.055)  (10.805)   (6.853)   (3.774) 
##                                                               
## --------------------------------------------------------------
## Observations              104       104       104       104   
## Log Likelihood         -474.470  -453.217  -487.381  -471.532 
## Akaike Inf. Crit.       976.939   958.434   982.762   955.063 
## Bayesian Inf. Crit.                         993.340   970.930 
## ==============================================================
## Note:                              *p<0.1; **p<0.05; ***p<0.01
library(texreg)
screenreg(list(m1_lme, m2_lme))
## 
## ======================================================
##                               Model 1      Model 2    
## ------------------------------------------------------
## (Intercept)                     14.27 *      14.27 ***
##                                 (6.85)       (3.77)   
## sex1                            45.00 ***    45.00 ***
##                                 (4.84)       (8.32)   
## ------------------------------------------------------
## AIC                            982.76       955.06    
## BIC                            993.34       970.93    
## Log Likelihood                -487.38      -471.53    
## Num. obs.                      104          104       
## Num. groups: Region             13           13       
## Variance: Region.(Intercept)   458.23        82.27    
## Variance: Residual             609.04       411.59    
## Variance: Region.sex1                       693.73    
## ======================================================
## *** p < 0.001, ** p < 0.01, * p < 0.05
m3_lme <- lmer(death ~ sex + (sex|Region) + pop, data = irlsuicide)
## Warning: Some predictor variables are on very different scales: consider
## rescaling
## Warning in checkConv(attr(opt, "derivs"), opt$par, ctrl =
## control$checkConv, : Model failed to converge with max|grad| = 0.141106
## (tol = 0.002, component 2)
## Warning in checkConv(attr(opt, "derivs"), opt$par, ctrl =
## control$checkConv, : Model failed to converge: degenerate Hessian with 1
## negative eigenvalues
m4_lme <- lmer(death ~ sex*pop + (sex|Region), data = irlsuicide)
## Warning: Some predictor variables are on very different scales: consider
## rescaling
screenreg(list(m3_lme, m4_lme))
## 
## ======================================================
##                               Model 1      Model 2    
## ------------------------------------------------------
## (Intercept)                     -1.51         9.67 ***
##                                 (2.82)       (2.84)   
## sex1                            45.14 ***    20.69 ***
##                                 (7.60)       (4.77)   
## pop                              0.00 ***     0.00 ** 
##                                 (0.00)       (0.00)   
## sex1:pop                                      0.00 ***
##                                              (0.00)   
## ------------------------------------------------------
## AIC                            922.69       883.69    
## BIC                            941.20       904.85    
## Log Likelihood                -454.34      -433.85    
## Num. obs.                      104          104       
## Num. groups: Region             13           13       
## Variance: Region.(Intercept)     0.00        29.06    
## Variance: Region.sex1          623.41       144.48    
## Variance: Residual             256.70       147.01    
## ======================================================
## *** p < 0.001, ** p < 0.01, * p < 0.05

Centering the Independent Variables

library(magrittr)
irlsuicide %<>% mutate(cpop = pop - mean(pop))
m4a_lme <- lmer(death ~ sex*cpop + (sex|Region), data = irlsuicide)
## Warning: Some predictor variables are on very different scales: consider
## rescaling
screenreg(list(m4_lme, m4a_lme))
## 
## ======================================================
##                               Model 1      Model 2    
## ------------------------------------------------------
## (Intercept)                      9.67 ***    14.25 ***
##                                 (2.84)       (2.25)   
## sex1                            20.69 ***    45.15 ***
##                                 (4.77)       (4.09)   
## pop                              0.00 **              
##                                 (0.00)                
## sex1:pop                         0.00 ***             
##                                 (0.00)                
## cpop                                          0.00 ** 
##                                              (0.00)   
## sex1:cpop                                     0.00 ***
##                                              (0.00)   
## ------------------------------------------------------
## AIC                            883.69       883.69    
## BIC                            904.85       904.85    
## Log Likelihood                -433.85      -433.85    
## Num. obs.                      104          104       
## Num. groups: Region             13           13       
## Variance: Region.(Intercept)    29.06        29.06    
## Variance: Region.sex1          144.48       144.48    
## Variance: Residual             147.01       147.01    
## ======================================================
## *** p < 0.001, ** p < 0.01, * p < 0.05

Intra-Class Correlation

m0_lme <- lmer(death ~ 1 + (1|Region), data = irlsuicide)
summary(m0_lme)
## Linear mixed model fit by REML ['lmerMod']
## Formula: death ~ 1 + (1 | Region)
##    Data: irlsuicide
## 
## REML criterion at convergence: 1041
## 
## Scaled residuals: 
##     Min      1Q  Median      3Q     Max 
## -1.3181 -0.6837 -0.3082  0.3124  3.8787 
## 
## Random effects:
##  Groups   Name        Variance Std.Dev.
##  Region   (Intercept)  386.7   19.67   
##  Residual             1180.9   34.36   
## Number of obs: 104, groups:  Region, 13
## 
## Fixed effects:
##             Estimate Std. Error t value
## (Intercept)   36.769      6.411   5.735

To be honest, I wasn’t sure where to find the information to help me interpret these results. I decided to continue with the Bristol data as well, in case that is easier to interpret.