Different types of Scales in educational management/errors/characteristics 2020
There are 4 (four) basic way for quantifying a variable. they are also called levels of measurement and are commonly referred to as :
1.Nominal scale
2.Ordinal or Rank scale
3. Equal interval scale and
4. Ratio scale.
1. Nominal scale.
The nominal scale is the least precise or crude among the four basis scales of measurements. measurement on a nominal scale is simply assigning persons to qualitatively different categories. for example, people can be classified as male or female. if desired numerals can be assigned to each group. thus, males might be coded 1 and females 2. these numerals are used for identification only, to denote membership in a certain class, they do not only magnitude. we can, however, count the number of people in each group, for example, we might have 20 males (group 1) and 30 females (group 2).
2. Ordinal or Rank scale.
Ordinal scale rank people on some dimension. for examble, when we rank school children in order according to their height, from tallest to shortest, we cannot say how much taller one child is than another we can only compare their relative heights. thus, on an ordinal scale we have classification (two children can be the same height) and ranking (some children are taller than others) but can say nothing about the size of the scale units (how much taller one child is than another).
in many situation ranking is sufficient. if we want to select the 20 best math students from a class of 100, we have only to give a math test and identify the 20 highest scores. we do need to know how much higher they scored than the rest of the class; we only need to know that they obtained the highest scores. in general, when we are interested in selecting only a top (or bottom) group of people, ranking will suffice.
3.Equal interval scales;
on an interval scale, a difference of a certain magnitude means the same thing at all points along the scale. in other words, the score units can be shown to be equivalent at all points on the scale. thus, an interval scale involves, classification ranking and equal sized units. consequently, the crucial operation in the development of an interval scale is to establish that we do have equal sized units. we must be able to show that a given interval on the scale, say a 5 points difference is equivalent at any place on the scale.
the equal interval scale has the greater use in teaching learning situation, educational administration, educational guidance and counselling and educational research. the effectiveness of any instructional procedure can be evaluated precisely by collecting the data on this scale. the measurement in education is usually done on equal interval scale.
4. Ratio scales.
The fourth level of measurement is the ratio scale. in addition to equal intervals, ratio scales also have a meaningful zero point. since a define for most psychological characteristic (consider, for example, how to define ''zero intelligence'') and shall not be overly concerned with attempting to develop tests that measure on ratio scales.
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The Errors in educational measurement.
A good measuring instrument or test required some technical knowledge. it includes the knowledge and understanding of the various kinds of errors which influence the process of measurement. these are known as errors of measurement, and can be classified into four categories-
1.personal errors
2.variable errors
3.constant errors and
4. interpretive errors.
1. personal errors.
in the field of measurement, the term objectivity is used to designate that the characteristic is related to personal error. the persons observing exactly the same responses are likely to assign different scores, because they can see the performance inly from their own views or biases. the same person examining the same responses on two different occasions is likely to very. this is known as personal errors. it is termed as degree of objectivity.
2. Variable errors.
This kind of error may occur in psychological and educational measurement. the variable errors are those arising from accidents and inaccuracies due to many causes. a person making the observation which influences from time to time, test to test and individual to individual, is accountable to variable error. this is termed as degree of reliability.
3. constant errors.
Most of the measurement of education and psychology are indirect. it is neither possible nor desirable to open a person's skull, to look inside. an instrument measures what is claim to measure which is related to the trait or characteristics.
4. Interpretive errors.
The test score of an individual has no meaning until it is interpreted in terms of the performance of the other individuals or the performance of the group. interpretive errors are those which result from understanding as for one or two things-
a. with what short of group of the individual is being compared.
b. the way in which the comparison between the individual and the group performance is expressed.
interpretive errors may be stated that is the problem of translating the raw scores into the norms. this problems of interpretive errors is taken in care through a process called standardization. this type of error is measured through norms.
Characteristics of a good measuring instrument.
The characteristics of a good measuring instrument may be summarized in the following form;-
1.it should be objective
2.it should be reliable
3.it should be valid
4.it should be comprehensive and precise
5.it should be practicable.
the usability implies the following features-
1.Ease in administering the tool.
2. Ease in scoring the answer the answer scrips.
3.Ease in interpreting scores.
4. it should be economical from time, energy and money point of view.
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