shreeradhaIn censuses and large scale surveys, enumerators (persons who collect data are called as enumerators) are engaged to collect information from the persons concerned. They gather information in schedules or questionnaire specially prepared for the purpose in the form of answers given by the respondents to specific questions.
shreeradhaIt should be noted that the information collected through questions should be such that it is usable.
Advantages:
• It can be administered to large groups of individuals.
• It is much less time consuming and is economical.
• A much larger coverage can be made as people in distant places can be reached without much difficulty.
• It is advantageous in a situation where the persons concerned move to far away places. For example, in an enquiry relating to old students of a collage, such a method may be useful as students move out and away after leaving the institution.
shreeradhaQuestionnaires are usually administered on paper, in a structured or semi-structured format. Respondents often choose from among a set of forced-choice, or provided, responses. These can include yes/no or scaled responses. Questionnaires can be administered in person, by mail, over the phone, or via email/Internet.
shreeradhaThe indirect personal investigation is through some agencies that have intimate knowledge of the phenomenon under enquiry. For example, an investigator may collect information about cost of cultivation indirectly from village head instead of collecting the information from farmers.
Advantages:
• It is less time consuming and expensive.
• As information can be collected from more knowledgeable persons, these are expected to be more useful and reliable.
• As fewer persons need be contacted, the enquiry could be more extensive than in case of direct personal enquiry.
shreeradhaDispersion on the other hand is about, as in above case, whether majority of students have scored marks near the average or far away from the average. For example average of 1 and -1 is 0. Similarly average of 100 and -100 is also 0. In the first case data values are near the average i.e dispersion is less while in the second case data values are more scattered or spread or away from the average i.e dispersion is more. The most common measure of dispersion is the standard deviation
2.2 Methods of collection of primary data*
shreeradha(This blog site does not support formatting therefore sometimes there could be errors in the post.)
CHAPTER 2
Measures of Central Tendency And Dispersion
2.1 Introduction
In this chapter we will study various types of data, methods of data collection , data representation and measures of central tendency.
First question is ‘What is data’? Data is a set of something that we want to know about the object or objects under study. For example if we want to study performance of students in an examination, set of marks obtained by students will be our data.
shreeradha(This blog site does not support formatting therefore sometimes there could be errors in the post.)
Association.
Two variables are associated if variation in one variable has effect on variation in other variables.
Correlation.
It is a measure of association between variables.
Scatter Diagram or Scatter Plot
It is graph obtained by plotting of values of two variables which describe single bivariate observation (e.g. height and weight of a person). One variable (independent variable) X coordinate and the other variable (dependent variable) as Y coordinate.
shreeradha(This blog site does not support formatting therefore sometimes there could be errors in the post.)
Confidence Interval.
A confidence interval is percentage of observations that are supposed to lie in that interval. e.g. 95% confidence interval is supposed to contain 95% of observations according to the specified criteria.
Confidence Level
Confidence level is the confidence interval in which we expect to lie the given parameter of the hypothesis.
shreeradha(This blog site does not support formatting therefore sometimes there could be errors in the post.)
Hypothesis:
An Assumption of outcome of statistical testing is called as hypothesis. e.g.: Sample is as per required norms according to the given parameter.
Parameter
Parameter is criterion on which sample is accepted or rejected. Parameter could be mean, standard deviation etc.
Estimator.
Estimator is a parameter which is used to estimate the value of the population parameter. An example of an estimator is the sample mean, which is an estimator of the population mean.
