Should be a symbolic data table read with the function read.sym.table(...).
method
"cm" to Center Method and "crm" to Center and Range Method.
Value
predictsym.lm produces a vector of predictions or a matrix of predictions and bounds
with column names fit, lwr, and upr if interval is set. For type = "terms" this is a
matrix with a column per term and may have an attribute "constant"
References
LIMA-NETO, E.A., DE CARVALHO, F.A.T., (2008). Centre and range method
to fitting a linear regression model on symbolic interval data. Computational
Statistics and Data Analysis 52, 1500-1515.
LIMA-NETO, E.A., DE CARVALHO, F.A.T., (2010). Constrained linear regression models
for symbolic interval-valued variables. Computational Statistics and
Data Analysis 54, 333-347.