mm_run_reg: Build formula and run linear regression for metamodel
In DARTH-git/dampack: Decision-Analytic Modeling Package

Build formula and run linear regression for metamodel

1	mm_run_reg(analysis, dep, params, dat, type, poly.order, k)

`analysis`	either "oneway" or "twoway"
`dep`	dependent variable in regression
`params`	string vector with the name(s) of the parameter of interest. Defaults to all.
`dat`	data to use in regression
`type`	type of metamodel
`poly.order`	order of polynomial for the linear regression metamodel. Default: 2
`k`	the dimension of the basis used to represent the smooth term. The default depends on the number of variables that the smooth is a function of. `k` should not be less than the dimension of the null space of the penalty for the term (see `null.space.dimension`), but will be reset if it is. See `choose.k` for further information.
`all_params`	all params in PSA