Quality Control and Quality Assurance
If you want your monitoring efforts to be successful, you should have a Quality Assurance Project Plan (QAPP). A QAPP includes your monitoring plan, standard operating procedures (SOPs) for your monitoring methods, and all quality assurance measures to ensure proper data collection.
- Quality Assurance (QA) occurs before ever stepping out into the field. Quality assurance is having a plan that outlines all monitoring procedures, study design, how volunteers will be trained, quality control, data management, and data analysis.
- Quality control (QC) occurs during data collection. Quality control consists of the steps taken to ensure that all data collected is valid. This involves collecting field duplicates, field/trip blank, calibration blank, spike samples, and lab replicates and also that collected samples are representative of the true condition of the area being sampled.
- Quality assessment occurs after all the data has been collected. This is when the overall precision and accuracy of your analyzed data is assessed. Precision can be determined by calculating the standard deviation or calculating the percent difference between duplicate samples. Accuracy is determined by comparing your results to a known value, such as a standard.
This handy guide developed by the EPA should be your go-to if you are unfamiliar with terms in the other resources, unsure with the difference between precision and accuracy, or would like a list of acronyms you may encounter when developing your QA/QC procedures. At 46 pages, this document thoroughly includes all terms associated with quality assurance.
EPA developed this QAPP template specifically for EPA Region 2, but can be applied for projects in any location. Refer to this template to assist in writing your own QAPP or review its sections to add further detail to your own QAPP. Sample language is included in this template for each section to take the headache out of developing a QAPP.
This resource page from the Chesapeake Bay Program describes in detail why quality assurance plans are needed and what is required for an effective quality management plan. Here you can also find five of their approved quality assurance plans for their various projects. Note, because of the difference in each of their projects there are difference plans for each one.
This EPA tool includes six modules to guide you through the process of developing your own QAPP. Modules include general guidance, templates, an example QAPP, technical QA information, standard operating procedures for methods, and guidance on selecting a laboratory for sample analysis.
This webpage includes several USGS laboratories and their own quality assurance measures and systems. You will also find the USGS National Field Manual for the Collection of Water-Quality Data, which includes USGS specific protocols in various chapters. Refer to Chapters 1 and 4 for info on quality assurance and quality control.
Still hungry for more QA/QC resources?
Most states have their own resources for groups interested in monitoring. Refer to your state environmental agency for other resources that may be state specific and explore EPA’s Quality Assurance Handbook and Guidance Documents for more.