Research Techniques Made Simple: Sample Size Estimation and Power Calculation

Sample size and power calculations help determine if a study is feasible based on a priori assumptions about the study results and available resources. Trade-offs must be made between the probability of observing the true effect and the probability of type I errors (α, false positive) and type II errors (β, false negative). Calculations require specification of the null hypothesis, the alternative hypothesis, type of outcome measure and statistical test, α level, β, effect size, and variability (if applicable). Because the choice of these parameters may be quite arbitrary in some cases, one approach is to calculate the sample size or power over a range of plausible parameters before selecting the final sample size or power. Considerations that should be taken into account could include correction for nonadherence of the participants, adjustment for multiple comparisons, or innovative study designs. Sample size and power calculations help determine if a study is feasible based on a priori assumptions about the study results and available resources. Trade-offs must be made between the probability of observing the true effect and the probability of type I errors (α, false positive) and type II errors (β, false negative). Calculations require specification of the null hypothesis, the alternative hypothesis, type of outcome measure and statistical test, α level, β, effect size, and variability (if applicable). Because the choice of these parameters may be quite arbitrary in some cases, one approach is to calculate the sample size or power over a range of plausible parameters before selecting the final sample size or power. Considerations that should be taken into account could include correction for nonadherence of the participants, adjustment for multiple comparisons, or innovative study designs. CME Activity Dates: 19 July 2018Expiration Date: 18 July 2019Estimated Time to Complete: 1 hourPlanning Committee/Speaker Disclosure: All authors, planning committee members, CME committee members and staff involved with this activity as content validation reviewers have no financial relationships with commercial interests to disclose relative to the content of this CME activity.Commercial Support Acknowledgment: This CME activity is supported by an educational grant from Lilly USA, LLC.Description: This article, designed for dermatologists, residents, fellows, and related healthcare providers, seeks to reduce the growing divide between dermatology clinical practice and the basic science/current research methodologies on which many diagnostic and therapeutic advances are built.Objectives: At the conclusion of this activity, learners should be better able to:•Recognize the newest techniques in biomedical research.•Describe how these techniques can be utilized and their limitations.•Describe the potential impact of these techniques.CME Accreditation and Credit Designation: This activity has been planned and implemented in accordance with the accreditation requirements and policies of the Accreditation Council for Continuing Medical Education through the joint providership of Beaumont Health and the Society for Investigative Dermatology. Beaumont Health is accredited by the ACCME to provide continuing medical education for physicians. Beaumont Health designates this enduring material for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.Method of Physician Participation in Learning Process: The content can be read from the Journal of Investigative Dermatology website: http://www.jidonline.org/current. Tests for CME credits may only be submitted online at https://beaumont.cloud-cme.com/RTMS-Aug18 – click ‘CME on Demand’ and locate the article to complete the test. Fax or other copies will not be accepted. To receive credits, learners must review the CME accreditation information; view the entire article, complete the post-test with a minimum performance level of 60%; and complete the online evaluation form in order to claim CME credit. The CME credit code for this activity is: 21310. For questions about CME credit email [email protected] CME Activity Dates: 19 July 2018 Expiration Date: 18 July 2019 Estimated Time to Complete: 1 hour Planning Committee/Speaker Disclosure: All authors, planning committee members, CME committee members and staff involved with this activity as content validation reviewers have no financial relationships with commercial interests to disclose relative to the content of this CME activity. Commercial Support Acknowledgment: This CME activity is supported by an educational grant from Lilly USA, LLC. Description: This article, designed for dermatologists, residents, fellows, and related healthcare providers, seeks to reduce the growing divide between dermatology clinical practice and the basic science/current research methodologies on which many diagnostic and therapeutic advances are built. Objectives: At the conclusion of this activity, learners should be better able to:•Recognize the newest techniques in biomedical research.•Describe how these techniques can be utilized and their limitations.•Describe the potential impact of these techniques. CME Accreditation and Credit Designation: This activity has been planned and implemented in accordance with the accreditation requirements and policies of the Accreditation Council for Continuing Medical Education through the joint providership of Beaumont Health and the Society for Investigative Dermatology. Beaumont Health is accredited by the ACCME to provide continuing medical education for physicians. Beaumont Health designates this enduring material for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Method of Physician Participation in Learning Process: The content can be read from the Journal of Investigative Dermatology website: http://www.jidonline.org/current. Tests for CME credits may only be submitted online at https://beaumont.cloud-cme.com/RTMS-Aug18 – click ‘CME on Demand’ and locate the article to complete the test. Fax or other copies will not be accepted. To receive credits, learners must review the CME accreditation information; view the entire article, complete the post-test with a minimum performance level of 60%; and complete the online evaluation form in order to claim CME credit. The CME credit code for this activity is: 21310. For questions about CME credit email [email protected] Summary Points•Sample size and power calculations help determine if a study is feasible based on a priori assumptions about the study results and available resources.•Calculations require specification of the null hypothesis, the alternative hypothesis, type of outcome measure and statistical test, one or two-sided α-level, β, effect size, and variability (if applicable).•Limitation: assumptions about the expected effect size and variability may have to be made without prior knowledge. •Sample size and power calculations help determine if a study is feasible based on a priori assumptions about the study results and available resources.•Calculations require specification of the null hypothesis, the alternative hypothesis, type of outcome measure and statistical test, one or two-sided α-level, β, effect size, and variability (if applicable).•Limitation: assumptions about the expected effect size and variability may have to be made without prior knowledge.