GENERAL STATISTICS NOTES
March 29, 1999

Statistics-

  • a set of procedures for describing, synthesizing, analyzing and interpreting quantitative data.

NOIR Scales-

  • emerge because different variables utilize varied ways of being measured, and thus, different kinds of data result.
  • different scales of measurement require specific statistics.
  • a statistic appropriate for a lower level of measurement may be applied to higher level data, since each subsequent scale has all characteristics of previous one.

The NOIR Scales

a.) Nominal-

  • lowest level of measurement, classifies persons or objects into mutually exclusive categories based upon shared characteristics.
  • categories may be true (persons/objects naturally fall into, such as sex, type of school), or artificial (operationally defined by the researcher, such as height, learning style).
  • not very precise, but sometimes necessary.

b.) Ordinal-

  • not only classifies, but also ranks objects of study in terms of degree of possession of characteristic of interest (e.g. most to least, highest to lowest).
  • amount of difference between ranks varies, so precision is not as much as desired.

c.) Interval-

  • has same characteristics as previous two, but rank intervals are equidistant.
  • type of scale utilized for intelligence and achievement tests.
  • problem is that minimum and maximum scores are arbitrarily assigned (WAIS has FSIQ of 40 as lowest possible score, but does not indicate absence of intelligence).

d.) Ratio-