Introduction to Sampling

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Introduction to Sampling: Overview

This topic covers concepts, such as, Sampling Method, Statistical Population, Random Sample, Probability Sampling, Simple Random Sampling, Table of Random Numbers, Method of using Random Number Table & Biased Sampling etc.

Important Questions on Introduction to Sampling

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A lottery method is an example of ____sampling

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The principle of  _____  is the partition of a population into different strata such that the two strata are different but the elements in each strata are similar.

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Sample size in the sampling method means

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Niheda considers taking as her sample the first six people arriving at work one morning to choose a representative sample of six employees from the 78 employees at her place of work.

Give two reasons why this method is unsatisfactory.

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Explain the method of using random number table.

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What is random number table?

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What is statistical population? Explain with example

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Which of the following is true about 'Sampling bias'

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A sampling method is called ____ if it systematically favours some outcomes over others.

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Explain the probability sampling technique for random selection process.

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Use the random number table to identify the first six random numbers, using the following criteria: Three-digit numbers starting at the top of the third column and reading across

682363533571329968032441362385365455930559948172326405880195309141666450818

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Systematic sampling method is Probability sampling.

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Dominic wishes to choose a random sample of five students from the 150 students in his year. He numbers the students from 1 to 150. Then he uses his calculator to generate five random numbers between 0 and 1. He multiplies each random number by 150 and rounds up to the next whole number to give a student number.

Dominic's first random number is 0.392. Find the student number that is produced by this random number.

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The random variable X has mean 30 and variance 36. The random variable X¯ is the mean of a random sample of 100 observations of X.  find the probability that the sample mean is greater than 31. (correct the answer up to three decimal places).

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The editor of a magazine wishes to obtain the views of a random sample of readers about the future of the magazine.

A sub-editor proposes that they include in one issue of the magazine a questionnaire for readers to complete and return. Give two reasons why the readers who return the questionnaire would not form a random sample.

The editor decides to use a table of random numbers to select a random sample of 50 readers from the 7302 regular readers. These regular readers are numbered from 1 to 7302. The first few random numbers which the editor obtains from the table are as follows.

49757802395203860882

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The editor of a magazine wishes to obtain the views of a random sample of readers about the future of the magazine.

Use these random numbers to select the first three members in the sample.

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Jyothi wishes to choose a representative sample of 5 students from the 82 members of her school year.

Jyothi decides to use another method. She numbers all the students in her year from 1 to 82. Then she uses her calculator and generates the following random numbers.

231492  762305  346280

From these numbers, she obtains the student numbers 23, 14, 76, 5, 34 and 62. Explain how Jyothi obtained these student numbers from the list of random numbers.

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Jyothi wishes to choose a representative sample of 5 students from the 82 members of her school year.

She considers going into the canteen and choosing a table with five students from her year sitting at it, and using these five people as her sample. Give two reasons why this method is unsatisfactory.

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Dominic wishes to choose a random sample of five students from the 150 students in his year. He numbers the students from 1 to 150. Then he uses his calculator to generate five random numbers between 0 and 1. He multiplies each random number by 150 and rounds up to the next whole number to give a student number.

Explain briefly why five random numbers may not be enough to produce a sample of five student numbers.

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Dominic wishes to choose a random sample of five students from the 150 students in his year. He numbers the students from 1 to 150. Then he uses his calculator to generate five random numbers between 0 and 1. He multiplies each random number by 150 and rounds up to the next whole number to give a student number.

Dominic's second student number is 104. Find a possible random number that would produce this student number.