Sampling theory defines a way to pick a sample that represents the population being studied. Key ideas that to understand sampling theory include: population group, target population, sampling or eligibility criteria, accessible population, elements, representatives, sampling frames, sampling methods or plans (Grove, Gray, & Burns, 2015, p. 250). Population-Group, individuals or component being studied. Examples would be People with an infant in the NICU, Individuals with Parkinsons disease aged 50-80, Improved plagiocephaly when head rounding interventions started in infancy. Target Population-Individuals that meet the criteria. Example being Females with multiple sclerosis, diagnosed on MRI aged 37 and older. Sampling or eligibility criteria-list of features vital for...