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{info}These are the generic, automated Quality Control (QC) functions that will be applied to various OOI data products.{info}

{note}In general the QC results use reverse Boolean logic. So, 0 means the value met the test conditions (e.g. for Global Range Test this would mean it exceeds the min/max) and is bad data, and 1 means it did not meet the test conditions and is good data.{note}

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h3. Locate the QC Flags in the Data
h5. Navigate to a Data Product and Initiate Download
[Navigate|CIUserDoc:Browsing and Navigating] to the data product of interest, and initiate [downloading data|CIUserDoc:Download Data].
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h5. Ensure QC Variables are Checked and Timeframe is Appropriate
*1: Use Slider Bar to Adjust Timeframe of Data* - Note that the download can take a significant amount of time because upon download the QC flags are computed, so ensure the slider bar for the time frame is adjusted appropriately for only the data of interest.
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*2: Combined Data Quality Control Flag* - Overview flag for alert purposes.
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*3: Check and/or Uncheck QC Variables of Interest* - The QC variables should be selected on the ERDDAP download page. The example shows (3a) Density and (3b) Practical Salinity test flags.
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*4: File Type or URL Display Options* - Choose the option that best meets the user needs for viewing and downloading the data and QC flags.
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*5: Submit* - Activates the download process, note that the process can take a significant amount of time depending on the variables and timeframe chosen. Also the remaining download process is browser dependent so follow regular browser actions for the rest of the download process.
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[!QC-data-download.png|width=100%,height=auto,border=0!|^QC-data-download.png]

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h5. Review QC Flags in Downloaded Data
The look of the information will be dependent on the browser used and format selected. The example shown here were using a Google Chrome browser and downloading a .csv file format.
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[!QC-flags-in-data.png|width=50%,height=auto,border=0!|^QC-flags-in-data.png]

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h3. Subscribe to Alert based on the QC Functions
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h3. Understand the Functions

h5. Global Range Test
* falls within a give range

h5. Spike Test
* individual data values that deviate significantly from surrounding data values

h5. Stuck Value Test
* repeated occurrence of one value in a time series

h5. Polytrend Test
* tests a time series for whether the data contain a significant portion of a polynomial

h5. Local Range Test
* testing if measurements fall into a user-defined valid range, varies with measurement location

h5. Gradient Test
* changes between successive data points fall within a certain range

h5. Propogate Flags
* propagates "bad" qc flags to another (derived) datase

*Source:* [https://github.com/ooici/ion-functions/tree/master/ion_functions/qc/README.txt]
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