Accuracy & Precision in Measurement WATCH—Look at your watch, what time is it? What if it were 1 hour ahead?—inaccurate, but still precise because it is moving at a CONSISTENT Rate around the dial.

Accuracy & Precision Accuracy: Precision: How close you are to the actual value Depends on the person measuring Precision: How finely tuned your measurements are or how close they can be to each other Depends on the measuring tool Determined by the number of significant digits

Accuracy & Precision may be demonstrated by shooting at a target. Accuracy is represented by hitting the bulls eye (the accepted value) Precision is represented by a tight grouping of shots (they are finely tuned)

Accuracy without Precision Accuracy & Precision Begin Activity No Precision & No Accuracy Precision without Accuracy

HITTING THE MARK Make 5 balls of equal size Drop the clay balls as close to the center of the target as possible from 1 meter height Try different methods to maximize precision and accuracy Write a detailed procedure Switch your procedure and conduct 3 trials of dropping the 5 balls Mark each spot with a colored marker.

Representativeness Degree to which the samples taken from the water body represent the environmental conditions of that water

Completeness Comparison of the minimum number of samples necessary tor meaningful data VS. Number of samples originally intended to be collected.

Comparability How well data can be compared with other data from the same project or data from another project PROTOCOLS / Standard Operating Procedures (SOP’s) a collection of detailed, written instructions designed to achieve uniformity of the performance of a specific task. A step by step instruction of how to complete the task

Reliability Combines: Accuracy Precision Representativeness Completeness Comparability

Ways to Increase Accruacy and Precision Technology: Simple Visual Observation Calibration Testing Kits- Company, Expiration Date

Data Quality Objectives Established by EPA Water Managers Rely on: Physical Chemical Biological Assessments

Accuracy Precision Representatvieness Comparability Reliablilty Procedures and protocols ensure: Accuracy Precision Representatvieness Comparability Reliablilty Give an accurate picture of the quality of water we are consuming and any remediation efforts that may be needed

Define Questions Collect Data Manage Data Interpret Data Present Data TAKE ACTION!!!