Environmental Engineering Reference
In-Depth Information
9
DATA VALIDATION
After the wind resource measurements are collected and transferred to an office com-
puting environment, the next step is to quality control (QC) and validate the data.
The purpose of this process is to ensure that only valid data are used in subsequent
analyses and that the data are as accurate as possible. Problems overlooked at this
stage can result in significant errors in the wind project's estimated energy production.
While different analysts use different terminology, QC generally refers to the initial
screening of data for obvious problems such as logger and sensor failures and data
transmission failures. This should be done as soon as possible after the data are
transferred from the logger to ensure that instrument problems are discovered, and
fixed, promptly.
Data validation, a more involved process, is done less frequently (typically monthly
or quarterly). Validation means the inspection of data for completeness and reason-
ableness and the detection and flagging of bad (invalid or suspect) values in the data
record. A number of methods, which are described in detail in this chapter, can be
used. It should be noted, however, that no data validation procedure is likely to catch
every bad record, and moreover, good data may sometimes be wrongly rejected. Data
validation is like any statistical decision process subject to both type I (false positive)
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