Collection of Data - Class 11 Economics - Chapter 2 - Notes, NCERT Solutions & Extra Questions
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Notes - Collection of Data | Class 11 Statistics For Economics | Economics
Collection of Data: Class 11 Economics Notes for Students
Understanding how to collect data is a fundamental aspect of economics and various other subjects. This chapter provides insights into various methods and techniques for gathering data, which is crucial for analysing and solving economic problems.
Introduction to Data Collection
Definition and Importance
Data collection refers to the process of gathering information from various sources to provide a basis for analysis. It is essential as it allows researchers and economists to understand issues, trends, and correlations within various phenomena.
Purpose in Economics
In economics, the primary purpose of collecting data is to provide evidence for addressing specific problems and making informed decisions. The data helps economists to track and analyse variables such as production levels, income, consumption patterns, and more.
Primary and Secondary Sources of Data
Distinction Between Primary and Secondary Data
Data can be classified into two main categories:
- Primary Data: This data is gathered firsthand by the researcher for a specific purpose. Examples include surveys, interviews, or experiments.
- Secondary Data: This data is collected by someone else and repurposed by the researcher. Examples include government reports, articles, books, and websites.
Examples and Significance of Each
Primary data offers specific insights for particular research needs, while secondary data helps save time and resources by using already available information.
Modes of Data Collection
Different Modes of Data Collection
Various methods are employed to gather data effectively:
Personal Interviews
This method involves face-to-face interactions where the interviewer collects data directly from the respondent. It allows clarifications and deeper insights but is time-consuming and expensive.
Mailing Surveys
Questionnaires are mailed to respondents who fill them out and return them. This method is cost-effective and allows reaching remote areas, but it might have a lower response rate.
Telephone Interviews
Interviewers ask questions over the phone, which is less expensive and covers a broader geographical area. However, it might not be suitable for all respondents, particularly those without phone access.
Census and Sample Surveys
Definition and Differences
A census involves collecting data from every member of the population, providing more accurate data but at higher costs and time. Sample surveys involve collecting data from a representative group, which saves time and costs but might introduce sampling errors.
Example Applications
- Census: Conducted every ten years in India to gather demographic data.
- Sample Survey: A market research company studying consumer preferences by surveying a sample group.
Techniques of Sampling
Random Sampling
This technique ensures each member of the population has an equal chance of being selected. It reduces bias and provides more accurate results.
graph TD;
A[Random Sampling] --> B[Equal Chance of Selection];
B --> C[Reduces Bias];
Non-Random Sampling
In this technique, samples are selected based on convenience or judgement, which might introduce bias.
graph TD;
A[Non-Random Sampling] --> B[Convenience/Judgement Based];
B --> C[Possible Bias];
Preparation of Questionnaires
Guidelines for Creating Effective Questionnaires
- Keep it concise: Avoid lengthy questionnaires.
- Simple language: Use easy-to-understand questions.
- Logical order: Arrange questions from general to specific.
- Precision: Avoid ambiguous questions.
- Closed-ended vs Open-ended: Use a balance of both types.
Examples of Good vs. Poor Questions
- Poor: "Do you think smoking should not be prohibited?"
- Good: "Do you think smoking should be prohibited?"
Pilot Surveys
Definition and Purpose
A pilot survey is a small-scale trial run of the questionnaire to identify any issues before the main survey. It helps in refining questions and procedures.
Benefits of Conducting
Pilot surveys help in pre-testing the questionnaire, providing clarity on instructions, identifying ambiguities, and adjusting cost and time estimates.
Sampling and Non-Sampling Errors
Sampling Errors
These errors occur when there is a difference between the sample estimate and the actual population parameter. They can be reduced by increasing the sample size.
Non-Sampling Errors
These are more serious and include:
- Sampling Bias: Occurs when some population members are inadequately represented.
- Non-Response Errors: Arises when respondents do not participate, leading to unrepresentative samples.
- Errors in Data Acquisition: Happens due to mistakes in data recording or measurement.
Important Data Collection Agencies in India
Census of India
The Census of India, conducted every ten years, gathers comprehensive demographic data which includes population size, density, literacy rates, and more.
National Sample Survey Office (NSSO)
The NSSO conducts nationwide surveys on various socio-economic issues, including literacy, employment, and manufacturing activities.
Conclusion
Recap of Key Points
- Data collection is crucial for understanding and solving economic problems.
- Different methods such as personal interviews, mailing surveys, and telephone interviews have their unique advantages and challenges.
- Sampling techniques and preparing effective questionnaires are integral to the data collection process.
- Proper data collection methods minimise errors and ensure reliable and accurate research findings.
Importance of Proper Data Collection in Economic Research
Effective data collection is essential for accurate analysis and informed decision-making, impacting economic policies and strategies.
By understanding these fundamental aspects of data collection, Class 11 Economics students can grasp the importance of careful and precise methodologies in economic research.
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Extra Questions - Collection of Data | Statistics For Economics | Economics | Class 11
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Frame at least four appropriate multiple-choice options for following questions:
(i) Which of the following is the most important when you buy a new dress?
(ii) How often do you use computers?
(iii) Which of the newspapers do you read regularly?
(iv) Rise in the price of petrol is justified.
(v) What is the monthly income of your family?
(i) Which of the following is the most important when you buy a new dress?
A. Price
B. Brand
C. Quality
D. Style
(ii) How often do you use computers?
A. Every day
B. Several times a week
C. Once a week
D. Rarely
(iii) Which of the newspapers do you read regularly?
A. The Times
B. The Guardian
C. The Wall Street Journal
D. The Independent
(iv) Rise in the price of petrol is justified.
A. Strongly Agree
B. Agree
C. Disagree
D. Strongly Disagree
(v) What is the monthly income of your family?
A. Less than $2000
B. $2000 - $5000
C. $5000 - $10000
D. More than $10000
Frame five two-way questions (with 'Yes' or 'No').
Are market economies more efficient than command economies?
Does inflation always lead to higher interest rates?
Can fiscal policy influence unemployment rates?
Is free trade beneficial to all participating countries?
Do higher taxes always reduce economic growth?
State whether the following statements are True or False.
(i) There are many sources of data.
(ii) Telephone survey is the most suitable method of collecting data, when the population is literate and spread over a large area.
(iii) Data collected by investigator is called the secondary data.
(iv) There is a certain bias involved in the non-random selection of samples.
(v) Non-sampling errors can be minimised by taking large samples.
(i) True: There are indeed many sources of data.
(ii) False: Telephone surveys are suitable for literate populations but may not be effective for large areas where telephone access might be limited.
(iii) False: Data collected by the investigator is called primary data, not secondary data.
(iv) True: Non-random selection of samples can introduce bias.
(v) False: Non-sampling errors are related to data collection and recording errors, which are not mitigated merely by increasing the sample size.
What do you think about the following questions? Do you find any problem with these questions? Describe.
(i) How far do you live from the closest market?
(ii) If plastic bags are only 5 per cent of our garbage, should it be banned?
(iii) Wouldn't you be opposed to increase in price of petrol?
(iv) Do you agree with the use of chemical fertilisers?
(v) Do you use fertilisers in your fields?
(vi) What is the yield per hectare in your field?
The questions provided have some issues which can make gathering accurate and unbiased data challenging.
Subjectivity & Ambiguity:
(i) "How far do you live from the closest market?" is subjective and can vary based on respondent's perception of distance.
Leading Questions:
(ii) "If plastic bags are only 5 per cent of our garbage, should it be banned?" leads the respondent by presenting a percentage before soliciting an opinion.
(iii) "Wouldn't you be opposed to increase in price of petrol?" suggests that the respondent should be opposed.
Yes/No Influence:
(iv) "Do you agree with the use of chemical fertilisers?" simplifies the issue to a yes/no answer, which can limit the depth of insight.
(v) "Do you use fertilisers in your fields?" is straightforward but limits responses to a binary answer without context.
Precision Needed:
(vi) "What is the yield per hectare in your field?" requires precise quantitative data, which may be good but should ensure clarity about the measurement method.
You want to do a research on the popularity of Vegetable Atta Noodles among children. Design a suitable questionnaire for collecting this information.
Demographic Information:
Age of the child:
Gender: Male/Female/Other
Consumption Habits:
How often does your child consume noodles? (Daily/Several times a week/Weekly/Monthly/Rarely/Never)
How often does your child specifically consume Vegetable Atta Noodles? (Daily/Several times a week/Weekly/Monthly/Rarely/Never)
Preference:
How does your child rate the taste of Vegetable Atta Noodles? (1-5 scale)
Does your child prefer Vegetable Atta Noodles over other types of noodles? (Yes/No)
What are the reasons for their preference (e.g., taste, healthiness, texture)?
Purchase Decision:
Who usually decides the type of noodles to buy? (Parent/Child/Joint Decision)
Are you concerned about the nutritional content of the noodles your child consumes? (Yes/No)
Brand and Availability:
Which brand of Vegetable Atta Noodles does your child prefer?
How easily available are Vegetable Atta Noodles in your area? (Easily Available/Moderately Available/Not Available)
Advertisement Influence:
Has your child seen advertisements for Vegetable Atta Noodles? (Yes/No)
Do advertisements influence your child's preference for Vegetable Atta Noodles? (Yes/No/Maybe)
Health Perception:
Do you believe Vegetable Atta Noodles are healthier than regular noodles? (Yes/No/Not sure)
Open-ended Questions:
What improvements would you suggest for Vegetable Atta Noodles to make them more appealing to children?
Any other comments or feedback regarding Vegetable Atta Noodles?
In a village of 200 farms, a study was conducted to find the cropping pattern. Out of the 50 farms surveyed, $50 \%$ grew only wheat. What is the population and the sample size?
1. Population: The population refers to the total group of interest for a particular study. In this case, the population is all the farms in the village where the cropping pattern study is conducted. As stated, the village consists of 200 farms. Therefore, the population size is 200 farms.
2. Sample Size: The sample size is the number of units (e.g., individuals, farms, etc.) from the population that are actually studied or surveyed. In this study, 50 farms were surveyed to determine the cropping pattern. Thus, the sample size is 50 farms.
Give two examples each of sample, population and variable.
Sample:
A group of 100 randomly selected students from a university.
A set of 50 households from a city surveyed about their electricity usage.
Population:
All students in a university.
All households in a city.
Variable:
Age of individuals in a survey.
Monthly income of households in a study.
Which of the following methods give better results and why?
(a) Census
(b) Sample
Both census and sample methods have their own advantages and trade-offs:
Census:
Advantages: Provides complete and accurate data as it includes every member of the population.
Disadvantages: Time-consuming, expensive, and impractical for large populations.
Sample:
Advantages: Cost-effective, quicker, and feasible for large populations.
Disadvantages: May not be fully representative if the sampling method is flawed, potentially leading to biased results.
Better results depend on the context. For small populations, a census is preferable for accuracy. For large populations, a well-designed sample can yield reliable insights efficiently.
Which of the following errors is more serious and why?
(a) Sampling error (b) Non-Sampling error
Non-sampling errors are generally more serious than sampling errors. Here's why:
Sampling Error (a): This occurs due to the natural variability between different samples. It can be minimized by increasing the sample size and is usually predictable and quantifiable.
Non-Sampling Error (b): These errors are not related to the sample size and include data collection errors, nonresponse errors, and processing errors. They can introduce significant biases, are harder to detect, and cannot be reduced just by increasing the sample size.
Non-sampling errors can distort the data and lead to misleading conclusions, making them more severe.
Suppose there are 10 students in your class. You want to select three out of them. How many samples are possible?
To calculate the number of possible samples when selecting 3 out of 10 students, we use the combination formula.
The combination formula is:
$$\text{Number of combinations} = \frac{n!}{r!(n-r)!} $$
Where:
- \( n \) is the total number of items to choose from (in this case, 10 students),
- \( r \) is the number of items to choose (in this case, 3 students),
- \( ! \) denotes the factorial, the product of all positive integers up to that number.
So, plugging in the values:
$$ \text{Number of combinations} = \frac{10!}{3!(10-3)!}$$
$$ = \frac{10!}{3! \times 7!} $$
$$ = \frac{10 \times 9 \times 8}{3 \times 2 \times 1} $$
$$ = 120 $$
Therefore, there are 120 different samples possible when selecting 3 students out of 10.
Discuss how you would use the lottery method to select 3 students out of 10 in your class.
Using the lottery method to select 3 students out of 10 involves the following steps:
Assign Numbers: Assign a unique number to each student, from 1 to 10.
Prepare Slips: Write each number on a separate slip of paper and fold them.
Mix Slips: Place all slips in a container and mix them thoroughly.
Draw Slips: Without looking, draw three slips from the container one by one.
Select Students: Match the numbers on the drawn slips with the assigned numbers to identify the selected students.
Does the lottery method always give you a random sample? Explain.
The lottery method is a technique used to create a random sample where each member of the population is assigned a unique number, mixed, and then drawn at random. This method is widely recognized for promoting equal chances of selection for all members, which is a fundamental principle of random sampling.
However, while the lottery method theoretically ensures a random sample, its effectiveness can be compromised by practical issues. If the mixing is not thorough, it could lead to a non-random selection where some elements are more likely to be chosen than others. Additionally, the manual nature of this method might introduce human error, further deviating from perfect randomness. Therefore, while the lottery method aims for randomness, its execution must be meticulously controlled to truly achieve a random sample.
Explain the procedure for selecting a random sample of 3 students out of 10 in your class by using random number tables.
Here's a step-by-step procedure:
List Students: Number the students from 1 to 10.
Obtain Random Number Table: Use a random number table, which contains a sequence of randomly generated digits.
Spot Starting Point: Randomly choose a starting point in the table.
Group Digits: Group digits to form numbers (choose 2 digits per group, as our range is 10).
Select Numbers: Read groups of 2 digits until you have 3 unique numbers between 01 and 10. Ignore numbers outside this range or repeated numbers.
Match with Students: Correspond the selected numbers with the student list to get your sample.
Do samples provide better results than surveys? Give reasons for your answer.
Samples and surveys can both yield reliable results, but each has its advantages:
Samples:
Cost-effective: Sampling is usually less expensive than conducting a full survey.
Time-saving: Collecting data from a sample is faster.
Manageability: Easier to manage and analyze compared to large-scale surveys.
Surveys:
Comprehensive: Surveys provide a complete dataset by covering the entire population.
Accuracy: Reduces sampling error and provides a fuller picture.
Detail: Surveys often allow for more in-depth questioning.
Conclusion: Samples are preferred when time and cost are critical, whereas surveys are better for achieving comprehensive and detailed data.
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