azpro: azpro

In COUNT: Functions, Data and Code for Count Data

Description

Data come from the 1991 Arizona cardiovascular patient files. A subset of the fields was selected to model the differential length of stay for patients entering the hospital to receive one of two standard cardiovascular procedures: CABG and PTCA. CABG is the standard acronym for Coronary Artery Bypass Graft, where the flow of blood in a diseased or blocked coronary artery or vein has been grafted to bypass the diseased sections. PTCA, or Percutaneous Transluminal Coronary Angioplasty, is a method of placing a balloon in a blocked coronary artery to open it to blood flow. It is a much less severe method of treatment for those having coronary blockage, with a corresponding reduction in risk.

Usage

data(azpro)

Format

A data frame with 3589 observations on the following 6 variables.

los

length of hospital stay

procedure

1=CABG;0=PTCA

sex

1=Male; 0=female

admit

1=Urgent/Emerg; 0=elective (type of admission)

age75

1= Age>75; 0=Age<=75

hospital

encrypted facility code (string)

Details

azpro is saved as a data frame. Count models use los as response variable. 0 counts are structurally excluded

Source

1991 Arizona Medpar data, cardiovascular patient files, National Health Economics & Research Co.

References

Hilbe, Joseph M (2007, 2011), Negative Binomial Regression, Cambridge University Press Hilbe, Joseph M (2009), Logistic Regression Models, Chapman & Hall/CRC

Examples

data(azpro)
glmazp <- glm(los ~ procedure + sex + admit, family=poisson, data=azpro)
summary(glmazp)
exp(coef(glmazp))
#glmaznb < -glm.nb(los ~ procedure + sex + admit, data=azpro)
#summary(glmaznb)
#exp(coef(glmaznb))

Example output

Loading required package: msme
Loading required package: MASS
Loading required package: lattice
Loading required package: sandwich

Call:
glm(formula = los ~ procedure + sex + admit, family = poisson, 
    data = azpro)

Deviance Residuals: 
    Min       1Q   Median       3Q      Max  
-3.1987  -1.1451  -0.4756   0.5331  12.4784  

Coefficients:
            Estimate Std. Error z value Pr(>|z|)    
(Intercept)  1.49140    0.01539   96.91   <2e-16 ***
procedure    0.95738    0.01218   78.61   <2e-16 ***
sex         -0.13022    0.01179  -11.04   <2e-16 ***
admit        0.33307    0.01210   27.52   <2e-16 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

(Dispersion parameter for poisson family taken to be 1)

    Null deviance: 16265.0  on 3588  degrees of freedom
Residual deviance:  8968.9  on 3585  degrees of freedom
AIC: 22483

Number of Fisher Scoring iterations: 5

(Intercept)   procedure         sex       admit 
  4.4433339   2.6048728   0.8779003   1.3952480 

COUNT documentation built on May 2, 2019, 2:37 a.m.