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Chapter 13 - Improving the organization and management of extension
Many people measure their height in feet and inches and their weight in stone and pounds, to give just a few examples. Imperial units are used in many other places, for example, in many Commonwealth countries that are considered metricated, land area is measured in acres and floor space in square feet, particularly for commercial transactions rather than government statistics. Similarly, gasoline is sold by the gallon in many countries that are considered metricated.
The metric system is a decimal system of measurement based on its units for length, the metre and for mass, the kilogram. It exists in several variations, with different choices of base units , though these do not affect its day-to-day use. Since the s, the International System of Units SI is the internationally recognised metric system. Metric units of mass, length, and electricity are widely used around the world for both everyday and scientific purposes. It is the world's most widely used system of units , both in everyday commerce and in science.
The SI was developed in from the metre-kilogram- second MKS system, rather than the centimetre-gram-second CGS system, which, in turn, had many variants. During its development the SI also introduced several newly named units that were previously not a part of the metric system. The original SI units for the seven basic physical quantities were: . The mole was subsequently added to this list and the degree Kelvin renamed the kelvin.
There are two types of SI units, base units and derived units. Base units are the simple measurements for time, length, mass, temperature, amount of substance, electric current and light intensity. Derived units are constructed from the base units, for example, the watt , i. The SI allows easy multiplication when switching among units having the same base but different prefixes. To convert from metres to centimetres it is only necessary to multiply the number of metres by , since there are centimetres in a metre. Inversely, to switch from centimetres to metres one multiplies the number of centimetres by 0.
A ruler or rule is a tool used in, for example, geometry , technical drawing , engineering, and carpentry, to measure lengths or distances or to draw straight lines. Strictly speaking, the ruler is the instrument used to rule straight lines and the calibrated instrument used for determining length is called a measure , however common usage calls both instruments rulers and the special name straightedge is used for an unmarked rule. The use of the word measure , in the sense of a measuring instrument, only survives in the phrase tape measure , an instrument that can be used to measure but cannot be used to draw straight lines.
As can be seen in the photographs on this page, a two-metre carpenter's rule can be folded down to a length of only 20 centimetres, to easily fit in a pocket, and a five-metre-long tape measure easily retracts to fit within a small housing. The Australian building trades adopted the metric system in and the units used for measurement of length are metres m and millimetres mm.
Centimetres cm are avoided as they cause confusion when reading plans. American surveyors use a decimal-based system of measurement devised by Edmund Gunter in A link is abbreviated "lk," and links "lks" in old deeds and land surveys done for the government.
Time is an abstract measurement of elemental changes over a non spatial continuum. It is an apparently irreversible series of occurrences within this non spatial continuum. It is also used to denote an interval between two relative points on this continuum. Mass refers to the intrinsic property of all material objects to resist changes in their momentum.
Weight , on the other hand, refers to the downward force produced when a mass is in a gravitational field. In free fall , no net gravitational forces objects lack weight but retain their mass. The Imperial units of mass include the ounce , pound , and ton. The metric units gram and kilogram are units of mass. One device for measuring weight or mass is called a weighing scale or, often, simply a scale.
A spring scale measures force but not mass, a balance compares weight, both require a gravitational field to operate. Some of the most accurate instruments for measuring weight or mass are based on load cells with a digital read-out, but require a gravitational field to function and would not work in free fall. The measures used in economics are physical measures, nominal price value measures and real price measures. These measures differ from one another by the variables they measure and by the variables excluded from measurements.
In the field of survey research, measures are taken from individual attitudes, values, and behavior using questionnaires as a measurement instrument. As all other measurements, measurement in survey research is also vulnerable to measurement error , i. In order to get accurate results, when measurement errors appear, the results need to be corrected for measurement errors. Since accurate measurement is essential in many fields, and since all measurements are necessarily approximations, a great deal of effort must be taken to make measurements as accurate as possible.
Using physics, it can be shown that, in the gravitational field of the Earth, it should take any object about 0. However, the following are just some of the sources of error that arise:. These characteristics would be I the mean position that he occupies on the scale; 2 the range of opinions that he is willing to accept, and 3 that one opinion which he selects as the one which most nearly represents his own attitude on the issue at stake.
It should also be possible to describe a group of individuals by means of the scale. This type of description has been represented in a diagrammatic way by the frequency outline. Any ordinate of the curve represents the number of individuals, or the percentage of the whole group, that indorses the corresponding opinion.
For example, the ordinate at b represents the number of persons in the group who indorse the degree of militarism indicated by the point b on the scale. A glance at the frequency curve shows that for the fictitious group of this diagram militaristic opinions are indorsed more frequently than the pacifistic ones. It is clear that the area of this frequency diagram rep-resents the total number of indorsements given by the group. It is sufficient at this moment to realize that, given a valid scale of opinions, it would be possible to compare several different groups in their attitudes on a disputed question.
A second type of group comparison might be made by the range or spread that the frequency surfaces reveal. If one of the groups is represented by a frequency diagram of considerable range or scatter, then that group would be more heterogeneous on the issue at stake than some other group whose frequency diagram of attitudes shows a smaller range or scatter.
It goes without saying that the frequent assumption of a normal distribution in educational scale construction has absolutely no application here, be-cause there is no reason whatever to assume that any group of people will be normally distributed in their opinions about any-thing. It should be possible, then, to make four types of description by means of a scale of attitudes. These are I the average or mean attitude of a particular individual on the issue at stake; 2 the range of opinion that he is willing to accept or tolerate; 3 the relative popularity of each attitude of the scale for a designated group as shown by the frequency distribution for that group, and 4 the degree of homogeneity or heterogeneity in the attitudes of a designated group on the issue, as shown by the spread or dispersion of its frequency distribution.
This constitutes our objective. The heart of the problem is in the unit of measurement for the base line, and it is to this aspect of the problem that we may now turn. The only way in which we can identify the different attitudes points on the base line is to use a set of opinions as landmarks, as it were, for the different parts or steps of the scale.
The final scale will then consist of a series of statements of opinion, each of which. If we start with enough statements, we may be able to select a list of forty or fifty opinions so chosen that they represent an evenly graduated series of attitudes. The separation between successive statements of opinion would then be uniform, but the scale can be constructed with a series of opinions allocated on the base line even though their base line separations are not uniform.
For the purpose of drawing frequency distributions it will be convenient, however, to have the statements so chosen that the steps between them are uniform throughout the whole range of the scale. Consider the three statements, a, c, and d, in Figure r. The statements c and a are placed close together to indicate that they are very similar, while statements c and d are spaced far apart to indicate that they are very different. We should expect two individuals scaled at c and a, respectively, to agree very well in discussing pacifism and militarism. On the other hand, we should expect to be able to tell the difference quite readily between the opinions of a person at d and another person at c.
The scale separations of the opinions must agree with our impressions of them. In order to ascertain how far apart the statements should be on the final scale, one method, the method used in our experiment, is to submit them to a group of several hundred people who are asked to arrange the statements in order from the most pacifistic to the most militaristic.
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We do not ask them for their own opinions. That is another matter entirely. We are now concerned with the construction of a scale with a valid unit of measurement. There may be a hundred statements in the original list, and the several hundred persons are asked merely to arrange the statements in rank order according to the designated attitude variable. It is then possible to ascertain the proportion of the readers who consider statement a to be more militaristic than statement c. If the two statements represent very similar attitudes we should not expect to find perfect agreement in the rank order of statements a and c.
If they are identical in attitude, there will be about It is possible to use the proportion of readers or judges who agree about the rank order of any two statements as a basis for actual measurement. The psychological scale separation between any two stimuli can be measured in terms of a law of comparative judgment.
The practical outcome of this procedure is a series of statements of opinion allocated along the base line of Figure 1. The interpretation of the base-line distances is that the apparent difference between any two opinions will be equal to the apparent difference between any other two opinions which are spaced equally far apart on the scale. In other words, the shift in opinion rep-resented by a unit distance on the base line seems to most people the same as the shift in opinion represented by a unit distance at any other part of the scale.
Two individuals who are separated by any given distance on the scale seem to differ in their attitudes as much as any other two individuals with the same scale separation. In this sense we have a truly rational base line, and the frequency diagrams erected on such a base line are capable of legitimate interpretation as frequency surfaces. In contrast with such a rational base line or scale is the simpler procedure of merely listing from ten to twenty opinions, arranging them in rank order by a few readers, and then merely counting the number of indorsements for each statement.
That can of course be done provided that the resulting diagram is not interpreted as a frequency distribution of attitude. If so interpreted the diagram can be made to take any shape we please by merely adding new statements or eliminating some of them, arranging the resulting list in rank order evenly spaced on the base line.
Allport's diagrams of opinions  are not frequency distributions. They should be considered as bar-diagrams in which is shown the frequency with which each of a number of statements is indorsed. Allport's pioneering studies in this field should be read by every investigator of this problem.
Measuring Change and Driving Results with the Prosci Change Scorecard
Our own interest in the possibility of measuring attitude by means of opinions was started by Allport's article, and the present study is primarily a refinement of his statistical methods. The ideal unit of measurement for the scale of attitudes is the standard deviation of the dispersion projected on the psycho-physical scale of attitudes by a statement of opinion, chosen as a standard. It is a matter of indifference which statement is chosen as a standard, since the scales produced by using different statements as standards will have proportional scale-values.
This mental unit of measurement is roughly comparable to, but not identical with, the so-called "just noticeable difference" in psychophysical measurement. One of these methods is to submit all of the stimuli, in pairs, to the subjects for judgment. Each one of the stimuli is submitted to every subject in combination with every other stimulus in the whole series. For example, two statements would be given to the subject with the request that he indicate which of them is more in favor of the church.
This can of course be done but the task becomes prohibitive, practically, in two ways. In the first place the subjects would be fatigued or bored if they had to make this type of judgment for. In the second place the statistical labor required to determine the scale-values would also be prohibitive although it is more conceivable than to ask several hundred individuals to read 8, pairs of statements. When the stimuli are more easily and quickly judged than the comparison of two statements, the law of comparative judgment can be readily applied.
For example, when the stimuli consist of pairs of nationalities in which the subject is asked only to under-line the nationality that he would in general prefer to associate with, or when the stimuli consist of handwriting specimens presented in pairs so that the subject need only check that specimen which seems the more excellent, then the procedure is not so fatiguing.
The statistical labor is also reduced to proportions more easily handled when the stimulus series is not so long. Another procedure for the law of comparative judgment is to ask the subject to sort all of the specimens in a series in rank order. When the psychophysical series is much shorter, from fifteen to twenty or even forty, then the task of arranging the stimuli in rank order is not so forbidding.
But when the stimulus series consists of statements, most of which must be read every time the subject looks at them for sorting into a rank order, the task becomes unwieldy.
Measurement instruments and systems
For these practical reasons it was advisable to use another psychophysical method in the construction of our attitude scale. We decided to use the method of equal-appearing intervals which has long been in use in psychophysical experimentation. The detailed experimental application of this method to the construction of our attitude scale will now be described.
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Lloyd Gordon Ward retired , who is responsible for its content.
- Steven Spielberg and Duel: The Making of a Film Career.
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- Measurement instruments and systems.
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Permission is granted for inclusion of the electronic text of these pages, and their related images in any index that provides free access to its listed documents. Editors' notes We have included this monograph as part of the history of attitude scaling. The classical psychophysical experiments were devoted to the measurement of the subject's power to discriminate between lines of slightly different length, between slightly different weights that he lifted, between pairs of gray papers that differed slightly in bright- 2 -ness, and so on.
In all of these measurements, however, 3 there is no simple physical stimulus scale with which to match the psychological scale. What might such a tool be used 4 for? But such a total vote does not 5 indicate the relative frequency of extreme convictions either for or against the proposition in the two groups, nor does it indicate just how a proposition might be presented in order to command a majority acceptance. In devising a method of measuring attitude we have tried to get along with the fewest possible restrictions because sometimes one is tempted to disre- 6 -gard so many factors that the original problem disappears.
The concept "attitude" will be used here to denote the sum-total of a man's inclinations and feelings, prejudice or bias, pre- 7 -conceived notions, ideas, fears, threats, and convictions about any specific topic. A politician extends friendship and hospitality in overt action while hiding an attitude that he expresses more truthfully to an intimate 8 friend. Similarly, it would be difficult to discover attitudes on sex liberty by a writ- 10 -ten questionnaire, because of the well-nigh universal pressure to conceal such attitudes when they deviate from supposed conventions.
A scale or linear continuum is implied when we say that a man has more education than another, or that a woman is more beautiful 11 than another, even though, if pressed, we admit that perhaps the pair involved in each of the comparisons have little in common. It is preferable to use an objective and experimental 12 criterion for the elimination of opinions that do not belong on the specified continuum to be measured, and we believe that such a criterion is available.
The point and its immediate vicinity rep-resent for our purpose an attitude, and we want to know relatively 13 how common that degree of feeling for or against pacifism may be in the group that is being studied. To the extent that the statement is indorsed or rejected by factors other than the attitude variable that it represents, to that extent the statement is useless for our purposes.
In fact, an attitude, practically speaking, is represented by a certain narrow range or 14 vicinity on the scale. The 16 diagram can be arranged in several different ways that will be separately discussed. The final scale will then consist of a series of statements of opinion, each of which 17 is allocated to a particular point on the base line. If they are identical in attitude, there will be about 50 18 per cent of the readers who say that statement a is more militaristic than statement c, while the remaining 50 per cent of the readers will say that statement c is more militaristic than statement a.
The reason why this ideal unit of measurement, the discrim- 20 inal error, could not be used in-the present study is as follows: The law of comparative judgment can be used in two ways, neither of which was directly applicable to the present problem for practical rather than for logical reasons. In the first place the subjects would be fatigued or bored if they had to make this type of judgment for pairs of statements, each pair requiring careful reading.
The usual psychophysical problem does not involve so many 21 stimuli in each series and the number of judgments is thereby reduced to a more reasonable magnitude.
Notes Sections of this monograph are reprinted, with permission of the editors, from L. For a more detailed discussion of this law see L. The logic of the psycho-logical S-scale is discussed in L. A detailed application of the law of comparative judgment to a related problem in attitude measurement is described in L.
Floyd H. Allport, and D.