1.2.3. Experimental Methods of Getting Information.
Experimental methods of getting ipforma8on are used in the case, when library sources don't give an answer to redesigning and designing situations. Practically any information can be received with experimental methods. The question is to set up correct relationship between information value, cost and time for it's receiving. Experimental methods of getting information can be devided into physical and sociological.
Any research is connected with measurement of different kinds. While measuring it is very important to choose the scale correctly, as cost and accuracy of experiments depend upon it Usually six types of scales are used:
-proportional (for example, grams, centimeters, seconds, rubles);
-interval (for example, Celsius degrees, Fahrenheit degrees); interval scales are divided into relative and absolute (Kelvin degrees);
-multimeasuring (or numerical indices), each of which consists of
some simple measuring scales (for example, IVkm; m/sec);
-ordinal, or rank (for example, the first, the second, the third, very
good, good, satisfactory, bad, very bad); - partially ordered, or poorly ordered
(for example, grandfather, father, uncle, child, cousin);
-nominal or classifying (for example, colour, nationality, trade, code numbers).
Interval proportional scales are usually used for a quantitative measuring. The main difference between them is in the choice of a starting indication point (absolute zero or conventional point). For a nominal scale there are no any assumptions, except the demand of continuity of categories. Complementary dependences are assumed for the other scales.
The categories of ordinal scale are ranked according to the order of magnitude, but intervals between categories are not prescribed. The measurements, directly connected with the tasks and criteria of a project, are the most important in designing. As the tasks and criteria are only rarely can be changed with the help of usual promotional scale, it is very important to know scale of Lower order (rank, ordinal, nominal). The example of such ordering of parameterizes given in fig. 1.2.
The possibility of restricting -the sphere of mathematical and statistical calculations, which can be carried out with some mistakes and lowering of experiment cost is the practical result of difference between the scales.
Fig.1.2. The level of tractor driver's discomfort during tests of a tractor seat:
1 - sensation of contact;
2 - freezing;
3 - dull ache;
4 - sharp pain.
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