Relative Percent Difference III

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Relative Percent Difference III

Report Name: Relative Percent Difference III (example)

File Name: EarthSoft.Reports.Library.93818.dll

Dependencies: N/A

Software: EQuIS Professional and EQuIS Enterprise

Source: EQuIS Professional install

Language: English

Output Type: Excel1


Description: The Relative Percent Difference (RPD) III Report determines the difference between analytical results for up to three samples. This report can be used to compare sample results from different laboratories or locations.


Installation Instructions: This report assembly is part of the EQuIS Professional installation. No additional installation steps are necessary.



Users can select two or three samples for RPD analysis per run of the report. The Sample Information > Date Range > Start parameter requires input of the SAMPLE_DATE to populate the list of samples for user selection. The Sys Sample Code input selections filter to show only those SYS_SAMPLE_CODEs with SAMPLE_DATEs within one day of the input Start.


The report displays analytical results in the three columns of Primary, Secondary, and Tertiary, and displays the related detection limit information in separate columns.


The report calculates an RPD as the absolute value of the difference between two samples (original and replicate samples) divided by the average of the samples, and then expressed as a percentage.  


RPDs are calculated for three categories as follows.

Category1: Primary vs Secondary (Original vs Duplicate)  

Category2: Primary vs Tertiary (Original vs Triplicate)

Category3: Secondary vs Tertiary (Duplicate vs Triplicate)


For each of the Categories 1, 2, and 3, the report uses the logic below to 1) check the RPDs against the RPD Lower/Upper control limits (default or user-selected), and 2) check each of the two analytical results of calculating the RPDs against detection limits times user-defined Lower/Upper limit multiplier (default or user-selected), and 3) assign an appropriate outcome. When an RPD exceeds the control limits, it is highlighted.


For readability, the values from input parameters are abbreviated as follows:


Detection Limit:\Reporting Limit = RL


Detection Limit:\Lower Limit (required; defaults to 10) = DL_LL_multiplier


Detection Limit:\Upper Limit (required; defaults to 20) = DL_UL_multiplier


Relative Percent Difference:\RPD Lower Limit (required; defaults to 30%) = RPD_LL


Relative Percent Difference:\RPD Upper Limit (required; defaults to 50%) = RPD_UL


The four outcomes for the Category 1~3 evaluations (Pass, Pass 1, Pass 2, or Fail) are determined as follows:





Pass 1:  

RPD ≤ RPD_LL, and

Each of the two (2) sample results < (use ≤ if UseEqualToInUpperLimit=True) DL_LL_multiplier * RL.  


Pass 2:  

RPD < RPD_UL, and  

Each of the two comparison sample results ≥ DL_LL_multiplier * RL, and  

Each of the two comparison sample results < DL_UL_multiplier * RL

OR, if input selection UseEqualToInUpperLimit=True:


RPD ≤ RPD_UL, and

Each of the two comparison sample results > DL_LL_multiplier * RL, and

Each of the two comparison sample results ≤ DL_UL_multiplier * RL


Fail: Fail Is identified If Pass, Pass 1 and Pass 2 are not identified.  


When a Category of an RPD is Fail, the RPD is grey-color highlighted.



If the units of measurement for the primary, duplicate, and triplicate samples are different, select Unit(s) or Analyte\Analyte Group(s) to unify units (and ensure necessary unit conversion factor(s) is present).

This report requires related primary and duplicate and/or triplicate sample, test, and result data; matching units and/or unit conversion factors present.


Warning: Older databases may contain double "Reportable Result(s)" in the published report. The @reportable parameter was replaced by @reportable_results over time. If both parameters exist in ST_REPORT_PARAMETER, the conflict will prevent the "Reportable Result(s)" parameter from working.


Resolution: The fix depends on the contents of ST_USER_REPORT_PARAMETER for user reports of this report. First, filter ST_USER_REPORT_PARAMETER with the REPORT_ID for the RPD II report, found in ST_REPORT.

Case 1 – Only @reportable (old parameter) exists:
Select all entries in the PARAM_NAME column, then Find and Replace '@reportable' with '@reportable_results'.

Case 2 – Both @reportable (old parameter) and @reportable_results (new parameter) exist:

a.Delete @reportable records for these user reports in ST_USER_REPORT_PARAMETER.

b.Have users double-check the "Reportable Result(s)" parameter in their user reports.

Case 3: Only @reportable_results (new parameter) exists:
No changes to ST_USER_REPORT_PARAMETER needed.


After resolving the duplicate parameters in ST_USER_REPORT_PARAMETER, delete the @reportable record for this report in ST_REPORT_PARAMETER.




Report Parameters



Parameter for selecting individual locations.


Parameter for selecting location groups.

Sample Information

Date Range

Parameter section to select the sample start date.

Sys Sample Code

Original Sys Sample Code (required)

Select the SYS_SAMPLE_CODE which indicates that this is the original sample.

Duplicate  Sys Sample Code (required)

Select the SYS_SAMPLE_CODE which indicates that this is a duplicate sample.

Triplicate  Sys Sample Code

Select the SYS_SAMPLE_CODE which indicates that this is a triplicate sample.


Parameter for selecting sample matrix.


Parameter for selecting analtye groups and individual analytes.


Parameter for selecting fraction.


Selection for analyte units.


Parameter selection for one or more task(s).

Delivery Group(s)

Parameter selection for the delivery group.

Reportable Result(s)

Parameter for selecting reportable results.

DQM Status

Parameter for selecting the DQM status.

Detection Limit

Reporting Limit (required)

Select which reporting limit you desire to use (reporting_detection_limit, method_deteciton_limit, etc.)

Non-detect multiplier

Indicate the non-detect multiplier. Default: 0.5

Non-detect handling

Select how non-detects are handled: eliminate non-detects or show all.

Lower Limit (required)

Indicate the lower limit of the detection limit multiplier standard. Default: 10

Upper Limit (required)

Indicate the upper limit of the detection limit multiplier standard. Default: 20

Relative Percent Difference

RPD lower limit (required)

Indicate the lower limit of the relative percent difference standard. Default: 30

RPD upper limit (required)

Indicate the upper limit of the relative percent difference standard. Default: 50

Replace < with <= in Checking Analysis Results for Category 1-3

Check box to replace < with <= in checking analysis results to determine Category 1-3

Enter the Maximum Number of Decimals for a Calculated Result

Enter one integer from 0 to 15.


1Excel report output requires a valid license of Microsoft Excel to view the output.