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# Unit 1 - PowerPoint PPT Presentation

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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## PowerPoint Slideshow about 'Unit 1' - mason-kent

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### Unit 1

Section 1-4

• 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

Telephone Surveys

• Inexpensive

• More candid than face-to-face interviews

• Many groups of people are not included in the survey for various reasons.

• Mailed Questionnaire Surveys

• Cover a wider area since they are less expensive

• People are more honest because they can remain anonymous

• Low number of responses

• Sometimes responses can be inappropriate

• Personal Interview Surveys

• Can get more in-depth answers

• High Cost

• Interviewer may be biased

• Alternate Methods of Acquiring Data

• Surveying Records

• Direct Observation

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.

• 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.

• 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.

• Other Sampling Methods

• Convenience Sampling- selects by doing whatever is convenient for the researcher.

• Sequential Sampling

• Double Sampling

• Multi-Stage Sampling

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

• Complete pg 29-30

• #’s 1 – 11, 14 – 19, 21 - 25