Learning Objectives: 1. Understand strategies for selecting a sample 2.Understand how to determine the required sample size

1. “ On Samples And Sampling” Title drawn from Elisabeth Kubler-Ross’ anagramatic phraseologies: “On death and dying” ; “On grief and grieving” ; “Real taste of life (On life and living) ” Ehi Igumbor School of Public Health University of the Western Cape

4. Populations and Samples Population (Group about whom you wish to gather data defined by person, place and time) Sample (Sub-group of total study population)

15. Types of Samples

24. Sampling Frame

28. Probability Sa mples- Simple Random

30. Probability Sa mples- Stratified Random

32. Probability Sa mples- Systematic Samples

34. Probability Sa mples- Cluster or Area Sample

71. EXAMPLE: Sample Size Calculation Where n = Sample size N = Population size e = Level of precision or Sampling of Error which is ± 5% Yamane’s formula: * Reference: Yamane, Taro. 1967. Statistics, An Introductory Analysis,2 nd Ed. New York: Harper and Row.

72. # of Health Facilities per Province Source: Digital Healthcare Solutions (PTY) LTD . Comprehensive Health Services Information for Southern Africa: Hospital & Nursing YearBook, 2007.

73. Sample Size Calculation: Total number of health facilities in the study: 350 *Reference: Yamane, Taro. 1967. Statistics, An Introductory Analysis,2 nd Ed. New York: Harper and Row.

75. Sampling Techniques Total # of health facilities Weighted Sample Eastern Cape 783 71 Free State 293 27 Gauteng 383 35 Northern Cape 124 11 KwaZulu-Natal 610 55 North West 398 36 Mpumalanga 280 25 Limpopo 499 45 Western cape 485 44 Total 3855 350

76. # of Facilities Selected for the study