 Hello Learners, I am Dr. Arsena Adhikari, today we will discuss about the remaining part of your unit number 1 from your paper 2 that is educational measurement. So in the last discussion we have discussed about the concept of measurement, what is educational measurement, what are its characteristics, its types and different functions of educational measurement. So today we will discuss about the scales of measurements, its meaning, classification of scales of measurement, different scales of measurement and what are the similarities and dissimilarities among the scales of measurement and at last we will summarize all the whole sector. So let's start. So measurement, in the field of measurement we have to apply some scales. So in future or in the further semester you will have some statistical part and there you have to apply some scales, some diss. So for this you have to be clear with the term scales of measurement. If you are clear with the scales of measurement it will be very easy for you to apply these scales in different kinds of statistics that will be applied in the field of education and psychology. So first of all we have to be clear about what is scales. So it refers to the ways in which numbers are defined and categorized. We know that in measurement we have to categorize the numbers or the values. So we have to assign some value in terms of the number. So when we refer, when we use or assign some measurement, some number in terms of some categorization it implies the scales of measurement. Each scale of measurement has certain properties or attributes which determine its applicability in certain mathematical or statistical analysis. I have already mentioned you that these scales will be applied in the field of statistics or in the field of measurement. So all the scales what we will discuss it have its own characteristics. So on the basis of the properties and attributes we will determine it, we will classify it and as per norms we will apply it. So scales of measurement which are also known as level of measurement. So you have to remember that the scales of measurement are also known as levels of measurement. So these are the classification that describe the nature of the information within the numbers assigned to variable. So in the field of education and psychology under the scope of measurement you will come across lots of variable and information. So we have to classify that and with the help of the level or what we call its scale of measurement we can get its appropriate nature. So now we have to know about the types of scales or what are the scales that are used in the field of measurement. So we all must remind this name Stanley Smith-Stavins. So he was the director of the Psychoacoustic Laboratory in Harvard University and he developed, he classified the scales of measurement into four categories and these scales are nominal, ordinal, interval and ratio. We all must be clear with these four scales of measurement that the first one is nominal, second one is ordinal, third one is interval and the fourth one is ratio. And I will mention here that among these four scales the interface scale is highly applicable in the field of education and psychology, while I will mention in the next slide. So now let's discuss about the scales in detail. So first, this is the first scale or which we can say it is the oldest scale of measurement and what is nominal scale when numerical data or numbers in measurement are used in simple identifiers or names they represent a nominal scale of measurement. So simply we can say that when we classify the variable or when we classify the information in terms of some names, some classification that is nominal scale. So in a class we have lots of students. So we classify it as male student or girl student or boy student. Like in a library we have lots of books so we classify it these are the books of education, these are the books of economics, these are the books from literature. So we can classify the information what information or what scale, what data we gain when we classify it in terms of numbers, in terms of some categories they are called as nominal scale. So in our day-to-day life, in our day-to-day activities we basically use this kind of scale and for example I have already given you the example but to be more clear we can say that the registration number of vehicle, pin code, phone number etc. are some of the example of nominal scale. So we can classify the people in terms of their color of hair, color of their eyes, blue color eyes or green color eyes or black color eyes people. So thus we can classify the people or data that we gather. So when we classify the data in terms of some numbers, in terms of some categories they are called as nominal scale. So this is the lowest level of scale and therefore it is considered as the lower scale of major men and here number are used only to represent categories of data. So you have to remember that here numbers are used only to represent the categories of data. We don't classify between the students that how many girls are there or how many boys are there. We just classify them to represent their presence. So the function of nominal scale is to just to represent the data in terms of some numbers. These scales are known as qualitative scale and measurement made on qualitative scale give qualitative data as we as these scale represent numbers only in terms of some categories. So these are basically qualitative data. So this is the qualitative scale and this give only the qualitative data. The number used in nominal scale are assigned as levels only and they have no specific numerical value or meaning that is why mathematical computation cannot be performed on nominal scale. Yes I have already mentioned that the function of nominal scale is only to represent data. It doesn't tell anything about the data. So in the mathematical computation this cannot be used or performed. So this is the lowest so from the statistical point of view this is the lowest level of measurement and also this is the oldest level of measurement. So this is about the nominal scale which is basically about representing data in terms of some number or categorization. Then we have the second scale that is ordinal scale. The name itself gives us a clue about the scale so ordinal. So when numbers used in major men represent an ordered series of relationship or rank order they represent an ordinal scale of measurement. So while in the classroom or in a school we have lots of students or children but we can get some data regarding their order of their assipment some of the higher, higher or higher assiver summer lower middle assiver summer lower assiver. So on the basis of this assipment we classify them as rule number one, rule number two, rule number three or first class, second class or third class like that. So ordinal scale implies representing data in terms of order. In terms of order it represents the order difference between the two children. So student rent in a class as a first, second or third represent the ordinal data. So simply it represents the data in terms of order. As ordinal scale gives information about the rank or order of the major. So it gives information about the order, what order the particular student possess. But it still doesn't provide information about the relative difference ok. We can adjust classify students in terms of or we can represent that he is rule number one or rule number two. But this scale doesn't provide us the actual difference between the rule number one and rule number two ok. So it is only represent the rank order only. It doesn't tell about the differences between the first class holder and second class holder. It just represent the order first, second, third like this. So this is about the ordinal scale of major one. Then we have the third scale of major one which I have already mentioned that this is the scale which is highly applicable in the field of majorment in the field of basically in the field of education and psychology. So what is interface scale? The name itself is interval. So it represents quantity and equal difference between successive interval on a scale in addition to the information about the order. Thus what this scale gives us information about the order first and second as well as it gives us the exact or equal difference between the order. Means it gives us it tells us about the interval. It tells us about the interval and therefore this is interval scale. So a perfect example of interface scale is a temperature scale that we use to measure the temperature of a particular person when he or she gets some favor ok. So but one thing is here is that it doesn't have a zero means when we measure a particular height or weight of a person we start from the zero point. We start from the zero point but here the interface scale doesn't have a zero point. So when a particular student suppose roll number 14 he gets 40 marks or he gets 15 marks and roll number 10 gets 30 marks. So it tells us difference if the interface scale gives us the accurate or exact difference between the roll number 10 and 13. But it doesn't mean that roll number 10 is double intelligence of the roll number 13. So we can say that the 5 kg or 10 kg or 25 kgs these are the example of ordinal scale. So it gives us the rank order. But in the field of education and psychology or in the field of behavioral science we cannot say that if ramp gain 50 then Rahim who get 25 is double intelligence than Rahim. We can't say that because this is in the field of behavioral science. So but it doesn't have a zero point. So for example zero decrease as says on a temperature scale doesn't signify absolute absence of temperature. In the field of education and psychology we cannot define or cannot find any person that he or she is he or she possess zero intelligence. No we can't say that but when we measure a weight or head we start from the zero point. So suppose this is the physical object and we can start it from the zero level but we cannot measure intelligence or what we can say personality and rest aptitude or whatever with a zero point. So this doesn't have a zero representation and therefore this is applied only in the behavioral science. Then we have the last scale that is ratio scale. So ratio scale means it has a true zero point. It has a true zero point which is absent in interval scale, ordinal scale or what we say in the first one is nominal scale. So the ratio scale of measurement represents quantity and equal difference between interval with an absolute true zero. So suppose we measure a length, a head of a room then we can get the absolute major measurement with a equal zero point. We can measure the length, we can measure the weight so with a true zero point. So it gives us equal difference between the intervals with a proper true zero. Then normally physical measurement such as I have already told you head, weight represent the ratio data. Because measurement invariably refer to define quantity where units are equal and zero means absolute absence of the dimension being major. All types of statistical measures are applicable to ratio scale. So you all must remember that all types of statistical measure are applicable to ratio scale. So these are the four scales of measurement which are very much important in the study of measurement in the field of education and psychology. So now we have to discuss the similarities and dissimilarities among the scale. From the discussion we have already clear about the similarities and dissimilarities but this table will help you more to know about the similarities and dissimilarities among the scales. So first I have classified it or showed it in a table. So as we noted that we have four scale and we have some factors or what we can say attributes. So first one is differentiate between variables. This is the first characteristics. Then second one is rank or rank order. Third one is indication of difference between the measures and fourth one is presence of absolute zero. So if we determine or if we analyze all the four scales first the all the four scale represent or all the four scale qualifies the first indicator or first attribute that it differentiate between the variable. All the four major scales of measurement differentiate between variable. Then regarding the rank order except nominal scale. Except nominal scale all other third scale that are ordinal interval and ratio gives rank order. Then except nominal and ordinal scale the last two interval and ratio scale indicates the degree of difference between the measures. It indicates the equal difference between the measures and regarding presence of absolute zero we all can say that except the first three the last measures of scales of measurement that is the ratio scale give habit absolute zero. So this table will help you to know about more about this four scales of measurement. Now we have come to the last point of the discussion. So as a summarization we can summarize the chapter or the discussion of today's is like that. The scale of measurement refers to the ways in which numbers are defined and categorized. So that was Stan Lee Smiths Devon who developed or classified the scales of measurement or level of measurement in four categories nominal, ordinal, interval and ratio. So nominal scale specifically mention or represent the data in terms of number or categorization. So we can say that numbers are used only to represent nominal scale. Then ordinal scale gives information about the rank or order of the measures. Then an interval scale represent quantity and equal difference between successive interval on the scale. And the last one that is ratio scale of measurement also represent quantity and equal difference between interval with an absolute or true zero. So on the basis of this discussion we can say that ratio order is the highest order of measurement because it has all the attributes of scales of measurement. So I think you have understood this particular unit. So if you have any question any queries you can put in the comment box we will try to answer it. So thank you very much.