Sampling design john ladaran


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Sampling Design is a process of obtaining information from a subset (sample) of a larger group (population) (webster 1985). This presentation is a partial fulfillment for a requirement for PA 298 Research for Social Science under Dr. Maria Theresa P. Pelones.

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Sampling design john ladaran

  1. 1. RESEARCHSAMPLING DESIGNS(PA 298 Research for Social Science)<br />Presented by:<br />Mr. John Ladaran<br />March 12, 2011<br />Presented to:<br />Maria Theresa P. Pelones, DM<br />
  2. 2. Sampling:<br /><ul><li>The process of obtaining information from a subset (sample) of a larger group (population) (webster 1985)
  3. 3. The act, process, or technique of selecting a suitable sample, or a representative part of a population for the purpose of determining parameters or characteristics of the whole population. (Mugo, Fridah)
  4. 4. used to make inferences about a population from a relatively small number of observations, that are assumed to be representative of the population. </li></ul>2<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  5. 5. Purpose of Sampling:<br />To draw conclusions about populations from samples<br />To accurately describe the parameters of a population based on the description (statistics) of a set of elements drawn from the population.<br />make generalizations about the whole [the population] which are valid [accurate] and which allow prediction. If this spoonful needs salt, then it's likely that this would be true for others as well.<br />3<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  6. 6. Terminologies:<br />Population<br /> * The entire group of people of interest from whom the researcher needs to obtain information<br />Sample<br /> * contacting a portion of the population (e.g. 10%)<br />Census<br /> * the entire population<br />Element<br /> * one unit from a population<br />4<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  7. 7. <ul><li> Two keys to be considered:</li></ul> 1.) Selecting the right people<br />Have to be selected scientifically so that they are representative of the population <br /> 2.) Selecting the right number of the right people<br />To minimize sampling errors<br />5<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  8. 8. Principles of sampling<br />Two keys:<br /> 1.) Selecting the right people<br /> - have to be selected scientifically so that they are representative of the population<br /> 2.) Selecting the right number of the right people<br /> - to minimize sampling errors<br />6<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  9. 9. Principles of sampling<br />Measure the sample using statistics in order to draw inferences about the population and its parameters<br />Population<br />sample<br />population<br />sample<br />parameters<br />statistic<br />7<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  10. 10. Principles of sampling<br />Characteristics of good samples<br />Truly Representative<br />Accessible<br />Low cost<br />Optimum size<br />Result can be applied universally with reasonable level of confidence<br />Similar to population<br />8<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  11. 11. Principles of sampling<br />sample<br />population<br />population<br />sample<br />9<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  12. 12. Advantages & Disadvantages<br />Sampling saves time and money<br />Sampling saves labor.<br />A sample coverage permits a higher overall level of adequacy than a full enumeration.<br />Complete census is often unnecessary, wasteful, and the burden on the public.<br /><ul><li>There is room for potential bias in the selection of suitable subjects for the research. This may be because the researcher selects subjects that are more likely to give the desired results, or that the subjects tend to select themselves.
  13. 13. Sampling requires a knowledge of statistics, and the entire design of the experiment depends upon the exact sampling method required.</li></ul>10<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  14. 14. Processes of Sampling Design<br />1.) Define the population<br />2.) Identify the sampling frame<br />3.) Select a sampling design or procedure<br />4.) Determine the sample size<br />5.) Draw the sample<br />11<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  15. 15. Processes of Sampling Design<br />Define Population<br />Determine sampling frame<br />Determine sampling procedure<br />Non-Probability Sampling<br />Probability Sampling<br />Sample Size<br />Execute sampling design<br />12<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  16. 16. 1.) Define the Target Population<br />It addresses the question “Ideally, who do you want to survey?”<br /><ul><li> It involves</li></ul> - defining the population units<br /> - setting population boundaries<br /> - screening<br />13<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  17. 17. 2) Determine the sampling Frame<br /><ul><li> Obtaining a list of population (how will you reach sample)
  18. 18. Problems with lists</li></ul> - omissions<br /> - ineligibles<br /> - duplications<br />14<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  19. 19. 3.) Selecting a Sampling Design<br /><ul><li> Probability Sampling</li></ul> - equal chance of being included in the sample<br /><ul><li>Non-probability Sampling</li></ul> - unequal chance of being included in the sample<br />15<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  20. 20. 4.) Sample Size<br />How large a sample should be?<br />Sample size constrains:<br /><ul><li>depends on the nature of the analysis to be performed
  21. 21. Desired precision of the estimates
  22. 22. Kind and number of comparisons
  23. 23. Number of variables that have to be examined
  24. 24. How heterogeneous a population is sampled. </li></ul>16<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  25. 25. Determination of Sample size<br />Nature of population<br /> -heterogeneous or homogenous<br /> -dispersion variability<br />Number of variables to be studied<br />Nature of groups and sub-groups proposed<br />Nature of study (quantitative or qualitative)<br /> -intensive & continuous or general survey<br />Type of sample<br />Intended depth of analysis<br />17<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  26. 26. Determination of Sample size<br />Precision and reliability<br />Level of non response<br />Available finance and other resources<br />Size of population<br />Nature of size of population<br />Size of questionnaire<br />18<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />
  27. 27. to be continue by….<br />MS. CHONA CASANOVA<br />ON DIFFERENT TYPE OF SAMPLING DESIGN<br />19<br />PA298 RESEARCH SAMPLING DESIGN<br />3/15/2011<br />