Which two scales of measurement always require nonparametric

Which two scales of measurement always require nonparametric procedures and why?

Solution

Which two scales of measurement always require nonparametric procedures and why?

Nominal and ordinal levels of measurement always require nonparametric procedures.

Non-parametric tests are used when assumptions of parametric tests are not met such as the level of measurement (e.g., interval or ratio data) or data does not follows normal distribution. when the outcome is an ordinal variable or a rank, the data does not follow a normal distribution.