Random errors were most likely to arise from coding errors in the database, but these errors were probably similar in both the exposed and unexposed cohorts.
Misclassification can result from coding errors, coding to rule-out conditions, and under- and over-coding.
Electronic databases such as EPC and NPR may contain errors arising from coding (Hoddevik 2005), data entry, transfers to other hospitals, and faulty extraction of data (Lofthus et al. 2005).
"It is a very intricate system, and coding errors can arise," Mr. Montalto said.
The largest number of invalid flag assignments arose from codes which represent two concepts in a single code.
The PTC 19.1 1988 code specifies procedures for the evaluation of uncertainties in individual test measurements, arising from both random errors and systematic errors, and for the propagation of random and systematic uncertainties into the uncertainty of a test result.
To minimize errors arising from incorrect coding region assignment, loci that included premature stop codons or more than one overlapping putative coding sequence (CDS) in a different reading frame or orientation were removed.
The ASME, Performance Test Code on Test Uncertainty: Instruments and Apparatus PTC 19.1 specifies procedures for evaluation of uncertainties in individual test measurements, arising from both random errors and systematic errors, and for the propagation of random and systematic uncertainties into the uncertainty of test results.
These include functional failures arising from design bugs, as well as operational failures arising from soft errors, severe process variations, and device aging.
All-against-all matching between the Gaussians is performed to avoid problems arising from alignment errors.
They find that fluctuations arising from such partitioning errors are difficult to suppress and can mimic noise in gene expression.
