panelmatch: Confidence ellipses around products based on panel descriptions

Description

Comparison of panels.

Usage

panelmatch(donnee, col.p, col.j, firstvar, 
    alpha = 0.05, coord = c(1,2), scale.unit = TRUE, nbsimul = 500, 
    nbchoix = NULL, centerbypanelist = TRUE, 
    scalebypanelist = FALSE, name.panelist = FALSE, cex = 1, 
    color = NULL, hierar = NULL)

Arguments

donnee

a list of data frames, each one made up of at least two qualitative variables (product, panelist) and a set of quantitative variables (sensory descriptors)

col.p

the position of the product variable (in each data frame, the same position)

col.j

the position of the panelist variable (in each data frame, the same position)

firstvar

the position of the first sensory descriptor (in each data frame, the same position)

alpha

the confidence level of the ellipses

coord

a length 2 vector specifying the components to plot

scale.unit

boolean, if T the descriptors are scaled to unit variance

nbsimul

the number of simulations (corresponding to the number of virtual panels) used to compute the ellipses

nbchoix

the number of panelists forming a virtual panel, by default the number of panelists in the original panel

centerbypanelist

boolean, if T center the data by panelist before the construction of the axes

scalebypanelist

boolean, if T scale the data by panelist before the construction of the axes (by default, FALSE is assigned to that parameter)

name.panelist

boolean, if T then the name of each panelist is displayed on the plotpanelist graph (by default, FALSE is assigned to that parameter)

cex

cf. function par in the graphics package

color

a vector with the colors used; by default there are 35 colors defined

hierar

hierarchy in the variable (see hmfa)

Value

A list containing the following elements:
eiga matrix with the component of the factor analysis (in row) and the eigenvalues, the inertia and the cumulative inertia for each component
coordinatesa list with: the coordinates of the products with respect to the panel and to each panelists and the coordinates of the partial products with respect to the panel and to each panelists
hotellingReturns a matrix with the P-values of the Hotelling's T2 tests for each pair of products: this matrix allows to find the product which are significatnly different for the 2-components sensory description
Returns a graph of the products as well as a correlation circle of the descriptors. Returns a graph where each product is displayed with respect to a panel and to each panelist composing the panel; products described by the panel are displayed as square, they are displayed as circle when they are described by each panelist. Returns a graph where each product is circled by its confidence ellipse generated by virtual panels. When a Multiple Factor Analysis is performed, returns a graph where each partial product is circled by its confidence ellipse generated by virtual panels.

References

Husson F., Le Dien S. & Pages J. (2005). Confidence ellipse for the sensory profiles obtained by Principal Components Analysis. Food Quality and Preference. 16 (3), 245-250. Pages J. & Husson F. (2005). Multiple Factor Analysis with confidence ellipses: a methodology to study the relationships between sensory and instrumental data. To be published in Journal of Chemometrics.

Examples

Run this code

data(chocolates)
Panel1=sensochoc[as.numeric(sensochoc[,1])<11,]
Panel2=sensochoc[as.numeric(sensochoc[,1])<21 & as.numeric(sensochoc[,1])>10,]
Panel3=sensochoc[as.numeric(sensochoc[,1])>20,]
res <- panelmatch(list(P1=Panel1,P2=Panel2,P3=Panel3), col.p = 4, col.j = 1, firstvar = 5)