1. Sample Selection Osama A Samarkandi, PhD, RN BSc, GMD, BSN, MSN, NIAC EMS 423; EMS Research and Evidence Based Practice

2. Determining sample design A sample design is a definite plan determined before any data are actually collected for obtaining a sample from a given population Probability samples; each element has a known probability of being included in the sample, Non-probability samples do not allow the researcher to determine this probability. Probability samples are those based on simple random sampling, systematic sampling, stratified sampling, cluster/area sampling whereas non-probability samples are those based on convenience sampling, judgment sampling and quota sampling techniques

3. Sample Designs 1.Deliberate sampling, 2.Simple random sampling, 3.Systematic sampling, 4.Stratified sampling, 5.Quota sampling, 6.Cluster sampling and area sampling 7.Multi-stage sampling 8.Sequential sampling

4. Collecting the data 1.Observation, 2.Personal interview, 3.Telephone interviews, 4.Mailing of questionnaires, 5.Schedules

5. Sample size calculations What is sample size? G-Power

6. Questions ?