Creates the optimal (D, U and I) designs for the accelerated life
    testing with right censoring or interval censoring. It uses generalized 
    linear model (GLM) approach to derive the asymptotic variance-covariance 
    matrix of regression coefficients. The failure time distribution is assumed 
    to follow Weibull distribution with a known shape parameter and log-linear 
    link functions are used to model the relationship between failure time 
    parameters and stress variables. The acceleration model may have multiple 
    stress factors, although most ALTs involve only two or less stress factors. 
    ALTopt package also provides several plotting functions including contour plot,
    Fraction of Use Space (FUS) plot and Variance Dispersion graphs of Use Space
    (VDUS) plot. For more details, see Seo and Pan (2015) <doi:10.32614/RJ-2015-029>.

Provides alternatives to the normal adjusted R-squared estimator for the estimation of the multiple squared correlation in regression models, 
              as fitted by the lm() function. The alternative estimators are described in Karch (2020) <DOI:10.1525/collabra.343>.

Evaluates land suitability for different crops production. 
  The package is based on the Food and Agriculture Organization (FAO) and the 
  International Rice Research Institute (IRRI) methodology for land evaluation. 
  Development of ALUES is inspired by similar tool for land evaluation, Land Use 
  Suitability Evaluation Tool (LUSET). The package uses fuzzy logic approach to evaluate 
  land suitability of a particular area based on inputs such as rainfall, temperature, 
  topography, and soil properties. The membership functions used for fuzzy modeling are 
  the following: Triangular, Trapezoidal and Gaussian. The methods for computing the 
  overall suitability of a particular area are also included, and these are the Minimum, 
  Maximum and Average. Finally, ALUES is a highly optimized library with core algorithms 
  written in C++.

Functions are designed to facilitate access to and utility with large scale, publicly available environmental data in R. The package contains functions for downloading raw data files from web URLs (download_data()), processing the raw data files into clean spatial objects (process_covariates()), and extracting values from the spatial data objects at point and polygon locations (calculate_covariates()). These functions call a series of source-specific functions which are tailored to each data sources/datasets particular URL structure, data format, and spatial/temporal resolution. The functions are tested, versioned, and open source and open access. For sum_edc() method details, see Messier, Akita, and Serre (2012) <doi:10.1021/es203152a>.