IdeTo: Spreadsheets for calculation and analysis of area under the disease progress over time data

Authors: Simko, Ivan

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2021
Publication Date: 11/9/2021
Citation: Simko, I. 2021. IdeTo: Spreadsheets for calculation and analysis of area under the disease progress over time data. Phytofrontiers. 1(3):244-247. https://doi.org/10.1094/PHYTOFR-11-20-0033-A.
DOI: https://doi.org/10.1094/PHYTOFR-11-20-0033-A

Interpretive Summary: Plant scientists working in the area of disease epidemics and, in particular, disease progress, have developed methods for mathematically summarizing disease development in a population. Area under the disease progress curve (AUDPC) is a method to combine repeated observations of disease progress into a single value. AUDPC systematically undervalues the effects of the first and last observations. Area under the disease progress stairs (AUDPS) improves the estimation of disease progress by giving a weight closer to optimal to the first and last observations. Both AUDPC and AUDPS can be calculated using commonly used statistical software such as SAS or R. Nevertheless, there is demand for a simple, Excel-based calculator for researchers not using SAS or R. ‘IdeTo’ is an Excel-based calculator that calculates AUDPC, AUDPS, and their standardized and relative forms (sAUDPC, sAUDPS, rAUDPC, and rAUDPS, respectively). The calculator allows entering data for up to 200 individuals evaluated at 200 timepoints. The calculator can be used to calculate the area under curve (AUC) for any trait where the trapezoidal approach is appropriate for fitting the data.

Technical Abstract: The area under the disease progress curve (AUDPC) and the area under the disease progress stairs (AUDPS) are used to combine data from repeated observations of disease progress into a single value. ‘IdeTo’, an Excel-based calculator, computes AUDPC, AUDPS, and their standardized and relative values for up to 200 individuals evaluated at 200 timepoints. The calculator provides the basic statistical description for the set of AUDPC and AUDPS values computed from analyzed individuals, and Pearson and Spearman correlation coefficients between AUDPC, AUDPS and another trait of interest. Three graphs are provided to visualize distribution of AUDPC and AUDPS values, and also their linear correlation with the trait of interest.