Unit 1
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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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Unit 1

Unit 1

Section 1-4


1 4 data collection and sampling techniques

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

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.


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    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


  • Unit 1

    Section 1-4

    Personal Interview Surveys

    • Advantages:

      • Can get more in-depth answers

  • Disadvantages:

    • High Cost

    • Interviewer may be biased


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    Section 1-4

    Alternate Methods of Acquiring Data

    • Surveying Records

    • Direct Observation


    Sampling

    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.


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    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.


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    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.


  • Other sampling methods

    Section 1-4

    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

    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


    Unit 1

    Homework

    • Complete pg 29-30

      • #’s 1 – 11, 14 – 19, 21 - 25


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