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In this chapter some preliminary terminologies have been provided which are very much useful and frequently used in dealing with the theory of sample surveys and its application.

Appendix - 1:
Physical Properties of Seed – bed / Puddled Soil

Tillage is the process of getting the soil ready for planting and maintaining it loose and weed-free while the crop is growing.  The main goal and core function of tillage are broken down into three phases:

1. Creating a suitable seedbed,
2.  Eliminating weed competition, and
3.  Enhancing the physical quality of the soil.

Important Definitions

• Sampling method or sampling technique is the process of studying the population by gathering information (on basis of samples) and analyzing that data.

• Population: The whole group we are interested in census.

• Census: A collection of data from the whole population

• Sample: A collection of data from part of the population

• Parameter Vs Statistics: Parameter is statistical measure pertaining to population whereas statistics is measure pertaining to sample.

• Estimate-Value of population parameter obtained from sample.

• Livestock census carried every 5 years (2019-20th livestock census)

Blood Sampling

Blood samples shall be taken in the early morning hours before offering any diet to human subjects or ration to livestock. The syringe and needle should be autoclaved, needle should be free from any blockage etc. In the case of ruminants, blood sample is taken directly from jugular vein, while in swine, blood sample is drawn from ear vein, while in human subjects, blood is taken from prominent vein on the inner surface of the yellow usually the (medium basilic). The container (test tube etc.) should be dried and autoclaved. We should separate plasma (from anticoagulent mixed blood) and serum from ordinary blood by centrifugation immediately. We should remember by heart  that blood samples should not be kept in deep freezer, because there are chances of haemolysis as well as an abnormal distribution of certain ions and enzymes between the cells and the serum. We should never force the blood through the needle as such type of practice may result in extensive hemolysis. We should discard first few drops of blood, while taking sample. We should prepare protein free filtrate immediately. Protein-free filtrate may be kept in a much better way than whole blood or plasma.

Air

Estimation of Total Suspended Particulate Matter (TSPM) and Respirable Suspended Particulate Matter (RSPM)

Requirements
Instrument

High Volume Sampler (HVS) APM 415-411 (Envirotech Instrument India), Respirable Dust Sampler (RDS) APM 451 (Envirotech Instrument India) with midget impinger containing absorbing solution were used.

7.1 Meaning of Sampling
    
Before we consider sampling theory, we first define the terms population and sample.
 
The word ‘population’ or ‘universe’ in statistics is used to refer to any collection of individuals or of their attributes or of results of operations which can be numerically specified. For example the assemblage of heights of all the individuals in the population is called a population of heights.  Similarly we may consider the population of weights, wages, yields of grain; prices of wheat, mileages of automobile tyres, etc. a population containing a finite number of individuals or members is called a finite population.  For instance the population f ages of the workers in a factory constitute a finite population of ages. A population with infinite number of members is known as infinite population.  For example the population of pressures of temperatures at various points in the atmosphere is an infinite population. 

For any statistical analysis, the required primary data are usually collected by the census or sampling methods. In the census method, the data are collected from all the individuals. E.g., If we want to study the weight of 100 cows, we have to make use of all 100 cows for data collection. That is, we collect data from the entire population or universe. However, in the sampling method, the data are collected from a small group of the population which is termed as the sample. A sample is a portion of the population selected to represent the population. E.g., we collect data only from a sample of cows, say 20 cows drawn from the population.

True/False

Q.1.    Collectivity (totality) of all sampling units is known as the “Population” and population size is denoted by “N”.
Q.2.    A list of all sampling units with their identification is known as “Sampling frame”. For example a list of all newly-born children in maternity home during a period of three months with specification of their sex, weight, name of their parents, their permanent address, etc. is known as sampling frame.
Q.3.    A function of all sampling units in the population is known as population parameter or population constant.

Soil testing is a useful tool that can help to ensure the efficient use of applied plant nutrients. Soil tests provide a means for assessing the fertility status of a soil, but soil tests do not provide a direct measure of the actual quantity of plant available nutrients in the soil. Instead, soil tests measure the quantity of a nutrient element that is extractable from a soil by a particular chemical extracting solution. The measured quantity of extractable nutrient in a soil is then used to predict the crop yield response to application of the nutrient as fertilizer, manure, or other amendment. As soil test levels increase for a particular nutrient, the expected crop yield response to additions of that nutrient decreases. A soil-testing programme has four phases as follows:

1.Collection of soil samples,

2.Chemical analysis of soil samples,

3.Calibration and interpretation of the results of chemical analysis, and

4.Nutrient/Fertilizer Recommendation.

9.1 Learning Objectives
After completing this chapter, you should be able to:
i) Understand the concept of Sample, Population, Sampling Frame, Sample Size, etc.;
ii) Differentiate between Probability and Non-Probability Sampling methods;
iii) Understand the various methods of sampling;
iv) Recognize Sampling and Non-Sampling errors;
v) Determine Sample Size.

Introduction

In 1952, the classical theory of survey sampling neared completion. In 1952, Horvitz and Thompson created a general theory with an aim to create objective estimations. As Horvitz and Thompson completed the Classical theory, the random sampling strategy was mostly agreed upon. The majority of the great books on sampling were written by numerous authors. (Yates, 1949; Deming, 1950; Hansen, Hurwitz, and Madow 1953; Cochran et al., 1953).

Why Sample?

• Particularly in fisheries, it is impractical to count every single specimen.

• Sampling gives a depiction of an organism's abundance and dispersion.

• A sufficient number of samples must be used to ensure that the results are accurate representations of the condition. Notwithstanding the fact that the sample is considered to be the credible and representative of the population and that the data shows accuracy, the sample may not accurately reflect the system's real population. As a result, sampling introduces a mistake.

• Sampling error is the statistical error showing the difference between the values derived from the sample of a population and the true values of a population parameter when all the units in the population are counted in the same way that the sample is counted.

A sample is just a part of a population selected according to some rule or plan. Following are some of the methods of sampling.

1. Simple Random Sampling

The simplest and the most commonly used type of probability sampling is simple random sampling. In this kind of sampling, each member of the population has the same probability of being included in the sample. Simple random sampling may be with or without replacement.

3.1. CENSUS AND SAMPLE SURVEYS

Census or Complete Enumeration

A survey, which includes every element of the population, is known as Census or the Method of Complete Enumeration. If certain agencies are interested in studying the total population of a country, they have to obtain information from all the households in rural and urban area.

The essential feature of this method is that this covers every individual unit in the entire population. We cannot select some and leave out others. We may be familiar with the Census of a country, which is carried out after a particular period like every ten years. A housetohouse enquiry is carried out, covering all households. Human demographic data on birth and death rates, literacy, workforce, life expectancy, size and composition of population, etc. are collected and published by a government agency.

Population: The word population or universe in statistics means a set of observations relating to a phenomenon under investigation.

Sample: It is a fraction or a subset of population drawn through a valid statistical procedure so that it can be regarded as representative of the entire population.

Sampling: The statistical procedure of drawing a sample from the population is called Sampling.

Census enquiry or complete enumeration: When each and every unit of the population is investigated for the characteristic under study, known as census enquiry or complete enquiry.

Sample enquiry or sample enumeration: It is a part of the population is investigated for the characteristic under study, known as sample enquiry or sample enumeration.

Necessity of sampling: Since, the process of collecting information from all the elements of a large population may be, in general, expensive, time consuming and difficult. We help to sampling and generalise the properties of the sample to the entire population. The statistical procedures which are used for drawing inferences or conclusions about the population from sample data are covered under Inferential Statistics or Statistical inference. Thus, sampling theory is the basis of statistical inference in which we wish to obtain maximum information about the population with minimum effort and maximum precision.

After having performed their function, pesticides in the parent form or in some converted form reach the soil, the ultimate sink for these moieties which are collectively termed as residues. According to FAO 1986, pesticide residue is defined as any substance or mixture of substances in food, agricultural commodities or animal feed resulting from the use of pesticides and includes any specified derivatives such as degradation products, metabolism, reaction products and impurities that are considered to be of toxicological significance. From the soil they move into other segments of the environment. The pesticide residues are absorbed by plants and enter the food chain, where they get concentrated in animal fat. Some residues are carried away by wind in the vapor form, which enables them to be transported to long distances from the source of application and then get collected by dust and rain before they are deposited on the ground again. Pesticide residues also move to aquatic environments through runoff, leaching, and atmosphere disposition.

INTRODUCTION

Management of several of the important insect-pests of crops is becoming increasingly difficult owing to a number of factors by which pests have been able to offset the effect of control interventions. Several of the present day pest management problems may be ascribed to the excessive and indiscriminate use of chemical pesticides during the last about three decades. Routine application of insecticides for controlling insect-pests, without taking into consideration whether economic damage to the crops is being inflicted by the pest or not, has resulted into several problems like pest resistance, pest resurgence, pest replacement, killing of natural enemies of pests, presence of toxic residues in food, and soil and environmental pollution, etc., apart from increase in the cost of plant protection. Entomologists have been trying to find solution to these problems through integrated pest management of which monitoring of insect activity through regular surveys is an important component. In fact, knowledge of insect activity is indispensable since pest management system can not operate without accurate estimates of pests and natural enemies population or without reliable assessment of plant damage and its effect on yield.

Sampling is the process of drawing a part of population supposed to be the representative of that population.

Types: Sampling process can be either random or non-random. Most frequently we use random sampling method in our studies. But sometimes the purpose of the study demands for non-random sampling in one or other phase of sampling (Example: When we want to study the impact of life skills development programme on the disabled female beneficiaries)

Sampoorna Grameen Rozgar Yojana (SGRY)

This scheme has been merged with NREGS since February 2006 so only most important points are given below.

1. The Sampoorna Grameen Rozgar Yojana (SGRY) was launched on 25 September, 2001 by merging the on-going schemes of EAS (Employment Assurance Scheme) and the JGSY (Jawahar Gram Samridhi Yojna)
2. Objective was to providing additional wage employment and food security, alongside creation of durable community assets in rural areas.
3. The annual outlay was Rs.10, 000 crore which included 50 lakh tones on food grains.
4. The cash component shared between the Centre and the States in the ratio of 75:25.