calculateAT6: Calculate Analytical Threshold

Description

Calculate analytical thresholds estimate using linear regression.

Usage

calculateAT6(data, ref, amount = NULL, weighted = TRUE, alpha = 0.05,
  ignore.case = TRUE, debug = FALSE)

Arguments

data

data.frame containing at least columns 'Sample.Name', 'Marker', 'Allele', and 'Height'.

ref

data.frame containing at least columns 'Sample.Name', 'Marker', and 'Allele'.

amount

data.frame containing at least columns 'Sample.Name' and 'Amount'. If NULL 'data' must contain a column 'Amount'.

weighted

logical to calculate weighted linear regression (weight=1/se^2).

alpha

numeric [0,1] significance level for the t-statistic.

ignore.case

logical to indicate if sample matching should ignore case.

debug

logical to indicate if debug information should be printed.

Value

data.frame with columns 'Amount', 'Height', 'Sd', 'Weight', 'N', 'Alpha', 'Lower', 'Intercept', and 'AT6'.

Details

Calculate the analytical threshold (AT) according to method 6 as outlined in the reference. In short serial dilutions are analysed and the average peak height is calculated. Linear regression or Weighted linear regression with amount of DNA as the predictor for the peak height is performed. Method 6: A simplified version of the upper limit approach. AT6 = y-intercept + t-statistic * standard error of the regression. Assumes the y-intercept is not different from the mean blank signal. The mean blank signal should be included in the confidence range ('Lower' to 'AT6' in the resulting data frame).

References

J. Bregu et.al., Analytical thresholds and sensitivity: establishing RFU thresholds for forensic DNA analysis, J. Forensic Sci. 58 (1) (2013) 120-129, ISSN 1556-4029, DOI: 10.1111/1556-4029.12008. http://onlinelibrary.wiley.com/doi/10.1111/1556-4029.12008/abstract