Readme file

SERIES C  
Applied Statistics

A hierarchical modelling approach for measuring reliability and agreement of two types of magnetic field dosimeter, by A.R Brazzale et al.
Appl. Statist., 53 (2004), 261-278

Two packages were used to analyse the EMDEX calibration data. The whole analysis was run in R except for the 95% prediction bounds reported in Tables 1 and 2 and the separate error variance estimates (sigma_1 and sigma_2 in Table 1) which were retrieved from SAS.

The EMDEX calibration data are hence provided in two formats.

* C5172-R.dat: data set for use in R (http://cran.r-project.org) included variables:

type = instrument type (two-level factor)
matr = serial number (to be read as 43-level factor)
coil = coil orientation (to be read as 3-level factor)
hz = frequency of the generated magnetic field
b.gen = generated magnetic flux density (in micro Tesla, numerical)
x = x-axis projection of the field vector (in micro Tesla, num.)
y = y-axis projection of the field vector (in micro Tesla, num.)
z = z-axis projection of the field vector (in micro Tesla, num.)
b.mis = measured field strength (in micro Tesla, numerical)
date = date of calibration
time = time of calibration

* C5172-sas.dat: data set for use in SAS (Release 8.2) included variables:
type = instrument type
matr = serial number
coil = coil orientation
hz = frequency of the generated magnetic field
bgen = generated magnetic flux density (in micro Tesla)
x = x-axis projection of the field vector (in micro Tesla)
y = y-axis projection of the field vector (in micro Tesla)
z = z-axis projection of the field vector (in micro Tesla)
bmis = measured field strength (in micro Tesla)
date = date of calibration
time = time of calibration
diff = absolute measurement error (response variable)
emdexii = dummy variable for EMDEX II meters
emdexlite = dummy variable for EMDEX Lite meters
bgenii = interaction term (between "bgen" and "emdexii")
bgenlite = interaction term (between "bgen" and "emdexlite")

The following files contain the code to reproduce the key steps of the analysis:

* C5172.R: code to be sourced into R (http://cran.r-project.org) -- prepared with Version 1.7.0 (2003-04-16)

* C5172.sas: code to be loaded into SAS -- prepared with Release 8.2 and the corresponding output obtained by sourcing/loading them:

* C5172.out: R Version 1.7.0 output

* C5172.lst: SAS Release 8.2 output

Alessandra Brazzale
Istituto di Ingegneria Biomedica
Consiglio Nazionale delle Ricerche
Corso Stati Uniti 4
35127 Padova
Italy

E-mail: alessandra.brazzale@isib.cnr.it

 Journals

SERIES A
Statistics in Society

SERIES B
Statistical Methodology

SERIES C
Applied Statistics

SERIES D
The Statistician