Nominal: A variable can be treated as nominal when its values represent categories with no intrinsic ranking (for example, the department of the company in which an employee works). Examples of nominal variables include region, zip code, and religious affiliation.
Ordinal: A variable can be treated as ordinal when its values represent categories with some intrinsic ranking (for example, levels of service satisfaction from highly dissatisfied to highly satisfied). Examples of ordinal variables include attitude scores representing degree of satisfaction or confidence and preference rating scores.
Scale: A variable can be treated as scale (continuous) when its values represent ordered categories with a meaningful metric, so that distance comparisons between values are appropriate. Examples of scale variables include age in years and income in thousands of dollars.
Descriptive statistics and statistical analysis&tests change according to scales of variables.
Frequency distribution, mode, pie and bar charts could be derived from the nominal variables.
Frequency distribution, mode, median, min-max values, range, bar chart could be derived from the ordinal variables.
Frequency distribution, mode, median, min-max values and range, mean(arithmetic, geometric, harmonic), variance, standard deviation, coefficient of deviation, percentile, interquantile range, skewness, kurtosis, moments, bar chart, histogram, box plot, scatter plot... could be derived from the scale variables.
Because of being required some assumptions, parametric tests are performed only for the scale variables.
Nonparametric tests could be performed for both scale, ordinal, nominal variables. It is possible to say that nonparametric tests are usually prefered to use for scale variables whether the assumptions of the parametric tests are violated.
If you go to the favourite links page of my website there is an electronic stats textbook and it has good descriptions of these terms. Thanks, Deborah Hilton Statistics Online
either you choose the level of measurement ot leave it to the default setting in SPSS. I found SPSS is smart to recognize the variable level of measurement.
Likert scales, levels of measurement and the “laws” of statistics
Norman, G. Adv in Health Sci Educ (2010) 15: 625. https://doi.org/10.1007/s10459-010-9222-y
Article LIkert scales, levels of measurement adn the “laws” of statistics
The equivalence of weighted kappa and the intraclass correlation coefficient as measures of reliability
JL Fleiss, J Cohen - Educational and psychological measurement, 1973Kappa is the proportion of agreement corrected for chance, and scaled to vary from-1 to+ 1 so that a negative value indicates poorer than chance agreement, zero indicates exactly chance agreement, and a positive value indicates better than chance agreement. A value of unity indicates perfect agreement. The use of kappa implicitly assumes that all disagreements are equally serious. When the investigator can specify the relative serious-ness of each kind of disagreement, he may employ weighted kappa, the proportion of
Journal Article
A Model for Agreement Between Ratings on an Ordinal Scale
Alan Agresti Biometrics Vol. 44, No. 2 (Jun., 1988), pp. 539-548 Published by: International Biometric Society DOI: 10.2307/2531866 Stable URL: http://www.jstor.org/stable/2531866 Page Count: 10