[R] regression with paired left-censored data

[Laura MacCalman]

HI

I am trying to analyse data which is left-censored (i.e. has values below the detection limit). I have been using the NADA package of R to derive summary statistics and do some regression. I am now trying to carry out regression on paired data where both my X and Y have left-censored data within them.

I have tried various commands in R:

rega = cenreg(Cen(conc, cens_ind) ~ Gp_ident)) 
with all X and Y data stacked and using a group identifier to look at the differences

this doesn't take account of the paired data though.

I have also tried splitting the data and regessing one on the other

rega = cenreg(Cen(conc1, censind1) ~ Cen(conc2,censind2))

which doesn't work.

Does anyone know of a command that will work - or perhaps suggest another package that I could use?

I have also looked at multiple imputation packages but they all seem to impute data depending on other columns - whereas I would want to impute data between zero and the censored value.

Any guidance/advice would be very much appreciated.

Laura


 
Dr Laura MacCalman Msci MSc PhD Gradstat
Senior Statistician

Institute of Occupational Medicine
Research Avenue North
Riccarton
Edinburgh
EH14 4AP

Tel: 0131 449 8078
Fax: 0131 449 8084
Mob: 07595 054 881
Email: Laura.MacCalman at iom-world.org

Web: http://www.iom-world.org
 

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