Overview of the min2HalfFFD R Package

Introduction

Welcome to min2HalfFFD, an intuitive and powerful R package designed for statisticians, experimental scientists, and researchers working with factorial experiments. This package generates all possible minimally changed two-level half-fractional factorial designs along with various statistical criteria to measure the performance of these designs through a simple, user-friendly shiny app interface. It includes the function minimal.2halfFFD(), which launches the interactive application where you can explore, compare, and select suitable designs. This vignette provides a quick overview of how to use the package and its shiny app interface.

What are Minimally Changed Factorial and Fractional Factorial Designs?

In many agricultural, post-harvest, engineering, industrial, and processing experiments, changing factor levels between runs can be physically difficult, time-consuming, or costly. Such experiments often involve hard-to-change factors or require a normalization period before stable operating conditions are reached. Because of these constraints, experimenters prefer run orders that keep the number of factor level changes to a minimum.

Minimally changed factorial and fractional factorial designs are constructed to address this practical need. They arrange the sequence of runs so that total factor changes are minimized, helping reduce operational effort, conserve resources, and lower the overall cost of experimentation.

This idea applies to both full factorial designs and fractional factorial designs. When a full factorial design contains too many treatment combinations to be feasible, a fractional factorial design—a carefully selected subset of the full design—offers a practical alternative.

Minimally Changed Run Sequences in Half-Replicate of $2^k$ Fractional Factorial Designs

In Design of Experiments (DOE) theory, the two levels of a factor can be represented as integers, e.g., –1 for the low level and 1 for the high level. A half replicate of a $2^k$ Factorial Designs ($\tfrac{1}{2} , 2^{k}$) with the minimum possible number of changes can be constructed by first developing a $2^{,k-1}$ factorial with minimal level changes in its run orders, and then generating a new factor by taking the product of all the