run three-way indscal

[maxheld83]

https://stats.stackexchange.com/questions/127167/non-metric-stress-in-3-way-multidimensional-scaling-indscal-individuals-vs-g

[maxheld83]

that might be the smacov package, as per https://stats.stackexchange.com/questions/47614/individual-differences-scaling-additional-investigations

also includes some suggestions for stress.