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Section 1.3 – Simple Random Sampling. Warm-Up. Identify the population and the sample. The average annual salary for 35 of company's accountants is $57,000. Determine if the variable is qualitative or quantitative and determine the level of measurement: a) State you were born in.
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Warm-Up • Identify the population and the sample. The average annual salary for 35 of company's accountants is $57,000. • Determine if the variable is qualitative or quantitative and determine the level of measurement: a) State you were born in. b) Percentage grade earned in your statistics class. 3) Determine if the variable is discrete or continuous. a) Temperature today in Palatine, IL. b) Number of people that enter Fremd today.
Random Sampling The process of using chance to select individuals from a population to be included in the sample
Steps for Obtaining a Simple Random Sample 1) Obtain a list of all the individuals in the population of interest. 2) Number the individuals from 1 to N, when N is the number of individuals in the sample. 3) Use a random number table, graphing calculator, or statistical software to randomly generate n numbers where n is the desired sample size.
SRS Class Example Number students 1 – class size. Student write number on small slip of paper. Randomly select 5 numbers from a bag to see who gets candy!
Obtaining a SRS using a Table In a study of wrap breakage during the weaving of fabric, one hundred pieces of yarn were tested. The number of cycles of strain to breakage was recorded for each yarn and the resulting data are given in the following table. Assign a number 1 - 100 Randomly select 10, 2-digit numbers from random number table Randomly Generated Number Table
Obtaining a SRS using TI-83/84 Math -> Arrow over 3 times to PRM -> Select 5:randInt( randInt(min value, max value, sample size)
SRS Example using TI-83/84 Joan’s small accounting firm serves 30 business clients. Joan wants to interview a sample of 5 clients in detail to find ways to improve client satisfaction. To avoid bias, she chooses an SRS of size 5. Here is the list of clients, with 30 two-digit labels attached: Obtain a sample of 7 businesses.