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Unit 1

Unit 1. Section 1-4. 1-4: Data Collection and Sampling Techniques. The most common method of collecting data is using surveys. Three of the most common surveying methods are: Telephone Surveys Questionnaires Surveys Personal Interview Surveys. Section 1-4. Telephone Surveys Advantages:

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Unit 1

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  1. Unit 1 Section 1-4

  2. 1-4: Data Collection and Sampling Techniques • The most common method of collecting data is using surveys. • Three of the most common surveying methods are: • Telephone Surveys • Questionnaires Surveys • Personal Interview Surveys

  3. Section 1-4 Telephone Surveys • Advantages: • Inexpensive • More candid than face-to-face interviews • Disadvantages: • Many groups of people are not included in the survey for various reasons.

  4. Section 1-4 Mailed Questionnaire Surveys • Advantages: • Cover a wider area since they are less expensive • People are more honest because they can remain anonymous • Disadvantages: • Low number of responses • Sometimes responses can be inappropriate

  5. Section 1-4 Personal Interview Surveys • Advantages: • Can get more in-depth answers • Disadvantages: • High Cost • Interviewer may be biased

  6. Section 1-4 Alternate Methods of Acquiring Data • Surveying Records • Direct Observation

  7. Section 1-4 Sampling • To obtain unbiased samples statisticians use four basic methods of sampling: • Random Sampling • Systematic Sampling • Stratified Sampling • Cluster Sampling • An unbiased sample is one where each subject in the population has an equally likely chance of being selected.

  8. Section 1-4 • Random Sampling – selects using chance methods or random numbers. • Previously, tables were used, now calculators are used. • Example: Nursing supervisors are selected using random numbers in order to determine annual salaries. • Systematic Sampling- selecting every kth subject of the group. • If the group has a population p and you want to sample s subjects, p/s = k. • Example: Every 100th hamburger manufactured is checked to determine its fat content.

  9. Section 1-4 • Stratified Sampling - selects by dividing the population up into groups by some characteristic that is important to the study, then sample from each group. • The groups are called strata. • Example: Mail carriers in a large city are divided into 4 groups according to gender and whether they walk or drive. Then 10 are selected from each group and interviewed. • Cluster Sampling- selects by dividing the population up into clusters and randomly selecting a few whole clusters as samples. • Example: In a large school district, all teachers from two of the school buildings are interviewed.

  10. Section 1-4 Other Sampling Methods • Convenience Sampling- selects by doing whatever is convenient for the researcher. • Sequential Sampling • Double Sampling • Multi-Stage Sampling

  11. Section 1-4 Creating a Random Number List (on the TI) • Press the Math button • Use the arrow key to scroll right until you are on the PRB menu • Select option #5: randInt( • Enter a starting value followed by a comma • Enter an ending value followed by a comma • Enter the number of values you wish to generate followed by a closed parenthesis • Press STO> • Press 2ndthen STAT • Select L1 Your random numbers will be stored in L1 for use

  12. Homework • Complete pg 29-30 • #’s 1 – 11, 14 – 19, 21 - 25

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