QMT 181 Chapter 1

1.6 Sampling

   - Sampling is a process of selecting sample based on the population of interest.
 
  - Sampling frame is a list of individuals or items from which the sample can be obtained.

    Advantages of Sampling

• Reduce the cost 
• Produce adequate information in shorter of period (reduce time spent).
• Provide information that is almost accurate as the result from a complete census.
• Reduce non-sampling errors due to a small number of respondents.

1.6.1 Terminologies in Sampling.

        - Probability Sample (Random Sample)

        Does not involve random selection. Used when sampling frames are difficult to obtain.
         Is considerably less expensive than doing probability sampling, but the results are of limited
         value.

• Simple Random Sampling
• Systematic Sampling
• Stratified Sampling
• Cluster Sampling
• Multistage Sampling

      - Non-Probability Sample ( Non-Random Sample)

       Any method of sampling that utilizes some form of random selection. In order to have a random
   selection method, you must set up some process or procedure that assures that the different
     unit in your population have equal probabilities of being chosen.

• Quota Sampling
• Judgmental Sampling
• Convenient Sampling

    

   1.7 Data Collection Method

         -method that commonly used by a researcher to get primary data.

• Direct Interview/ Personal interview.
• Telephone Interview.
• Mailed Questionnaire.
• Direct Observation.
• Online Surveys. 

1.8   Designing a Questionnaire.

     

   -Questionaire is a written instrument that contain  a series of questions or items that attempt collect       information on a particular subject.

      -Several steps to be considered when designing a Questionaire.

• Kept simple and phrase to imply the same meaning to all respondents.
• Specify the information to be collected.
• Questionnaire must be short as possible.
• Organized systematically and should have some kind of natural logic sequences.
• Avoid questions that need calculation.