Q….In questionnaire development stage, if researcher is not aware of about respondents’ inability to answer certain questions then that questionnaire cannot generate desired results. What parameter should researcher keep in mind to overcome respondent’s inability to answer the questions? Q.We want to obtain mean age of a magazine subscriber at 99% level of confidence is 2.58 . We want our result to be ± 2 of the true mean age. Suppose standard deviation is 5. What should be the sample size? given data: s=5 e=±5 z=99%=2.58 We know that: n= S2Z2/e2 put the value in formula Formula used for determining sample size is: n = S2 Z2 / e2 After using this formula, the answer obtained about the sample size might be in fraction. Examples for Determining Sample Size Example I We want to obtain mean age of a magazine subscriber at 99% confidence level. We want our result to be ± 2 of the true mean age. Suppose standard deviation is 5. What should be the sample size? Solution: e= ±2 s=5 z = 2.58 n = s2 z2 / e2 n = (5)2 (2.58)2 / (2)2 n = 41.6 or n = 42 A MS student gave a questionnaire to his supervisor for review. After completing the review, supervisor has underlined many questions and has given a common comment i.e. “leading questions; modify it”. What is a leading question? Explain with examples. Q.“The only difference between interval scale and ratio scale is that true zero exists in interval scale”. Is this statement true? If not, give reason to justify your answer. 3. Interval scale One problem with the ordinal scale is that it defines the order of the objects but it does not tell about what is difference (or distance) between the objects. Interval scale shows that as the interval between the numbers on the scale represent equal increments of the attribute being measured, the differences can be compared. A difference between 25 and 26 is the same as between 26 and 27 which is same as between 27 and 28. The most common example of interval scale in life is that of thermometer. But as you know two types of thermometer, Celsius and Fahrenheit do not have a fixed or true zero or freezing point. Both the zeros and units of measurements are different although the amount of heat in various intervals on each thermometer will be same. Let us illustrate it with figures. Amount of heat between 88o and 89o on Fahrenheit is same as between 91o-92o but amount of heat between 88o and 89o on Fahrenheit is different from amount of heat between 88o and 89o on Celsius. © Copyright Virtual University of Pakistan 37 Marketing Research (MKT611) VU Statistical techniques that are used in nominal and ordinal scales can also be used in interval scale. In addition to that, statistics like mean, standard deviation, product moment correlation etc. can also be used in interval scale. 4. Ratio scale Ratio scale is one in which a true zero exist. True zero or absolute zero means that number zero is assigned to the absence of the characteristic being measured. Thus we can compute ratio of scale values. For example, it is possible to say how many times greater or smaller one object is than another. This is the only type of scale that allows making comparison of absolute quantities. We can say that market share of company A is twice as much as of company B. In market research, data on number of customers, costs, sales, market share and some other marketing variables are measured on ratio scales. All statistical techniques can Q.Discuss the measurement problems associated with the semantic differential scale? ANSWER :Semantic Differential Scale This scale has been borrowed from another area of research called “semantics”. This scale contains a series of bipolar adjectives from the various characteristics of the object under study and respondents indicate the impression of each characteristic by indicating the appropriate place on the continuum. It is usually seven point rating scale having two poles (adjectives) e.g. “friendly unfriendly” “high quality-low quality” “convenient-inconvenient” or “dependableundependable”. Having seven separators between two poles is mandatory. While using the semantic differential scale, the respondent marks the blank that is closer to his rating. Look at the following example: Please indicate your impression about Restaurant A by marking the line that best describes your opinion. Quick service ------- slow service High prices ------- low prices Good quality ford ------- low quality ford Limited variety of ford ------- wide variety of ford Poor location ------- good location Semantic Differential Scale is gaining popularity because of its versatility. This scale is used extensively in comparing different brands, company images or stores. Mean is the statistics which is used in Semantic Differential Scales.