When alcohol test results are linked to access records or safety check histories, judgment text such as PASS and numbers such as 0.000 pile up on the same screen. Both results may seem to mean there is no problem, but if the device's output format and test mode differ, they are not the same information.
A screening method can produce a judgment such as PASS or FAIL for quick screening, while a quantitative method can display concentration as a number with a unit. OIML R 126-1:2021 also distinguishes analyzers that give quantitative results from preliminary screening in PASS/FAIL form. Storing a screening PASS as a quantitative result of 0.000 is not just matching the screen format. It changes the type of result the device originally produced and the scope in which it can be interpreted.
First separate what PASS refers to
The word PASS cannot be read straight away as a concentration of 0. Depending on the device, PASS may be a screening judgment based on a configured threshold, and its meaning can only be confirmed by also looking at the result codes or settings screen. When designing an integration, it is best to first check in the device manual and result code definitions whether PASS is a screening judgment or text linked to another procedural status.
Do not conclude from its shape that 0.000 means a quantitative test was completed, either. Store it as a concentration value only if it is confirmed that the device, in that mode, outputs the number and unit as a quantitative result. If an unconfirmed numeric notation cannot be told apart from a default or status value, the scope of later numerical analysis also becomes unclear.
Give each part of the result its own place within one record
Screening records and quantitative records do not have to be stored in separate systems. Instead, in a single test record, keep the test method, the result text shown by the device, the quantitative reading, the unit, and the settings applied at the time as separate pieces of information. It is better to avoid entering 0 in the quantitative reading field just to accommodate a screening result.
| What to store | Why keep it separately | Example on screen |
|---|---|---|
| Test method | Distinguishes the route by which screening and quantitative results were produced | Screening method, quantitative test method |
| Device result text | Preserves the original judgment such as PASS or FAIL | Device result: PASS |
| Reading and unit | Only records that output a quantitative value are interpreted as numbers | 0.000, unit shown by the device |
| Applied settings and raw output | Traces the judgment conditions at the time and the output before conversion | Applied settings information, raw result |
If no quantitative reading was produced during screening, the reading field can hold a value that shows the intent, such as N/A. A blank is hard to distinguish from a missed transmission or an interrupted test, but N/A shows that the result came without a reading. However, this label does not replace the device's raw output. It is a label for distinguishing result types on the storage screen.
Find the conversion error in a hypothetical case
As a hypothetical case, suppose a workplace first uses a screening method in safety checks and runs a quantitative test only when further confirmation is needed. The first record receives the device result text PASS, and the second receives 0.000, defined in the device specification as a quantitative value, along with its unit. If both records are stored as the number 0, they look like the same result in the list.
What to observe here is the difference that the first record has only result text, while the second has a reading and a unit. The interpretation does not focus on deciding whether PASS and 0.000 mean the same concentration, but on whether device outputs of different formats were turned into the same number. A possible action is to mark the screening method on the first record, keep the original PASS, and set the reading field to N/A.
The completion criterion is a state in which the list screen and downloaded data let you tell that the two records are different result types, and the original device output can be checked again. Once this criterion is met, combining the screens into one list does not combine the meaning of the results.
Define different targets for queries and statistics
For reports that calculate the average, maximum, or counts by range of quantitative readings, you can consider including only records confirmed as quantitative values. If PASS is stored as 0, judgment text gets mixed into the distribution of records that actually output a reading, and it becomes hard to tell what the report calculated. This does not mean screening records are unnecessary. It means numerical analysis and check histories answer different questions.
A history screen showing whether checks were performed can display screening and quantitative records together. In that case, show the test method and result type next to each result, and in quantitative value searches, show why screening records were excluded. It also helps interpretation not to combine the count of PASS results and the count of quantitative tests, but to present them separately as the number of records the device output as PASS and the number of records with a reading and unit stored.
Do not treat records already stored as 0 as confirmed values
If an existing system converted PASS to 0, first check whether the raw output sent by the device, the test method at the time, and the unit information remain. If this information exists, there is room to reclassify past records as screening or quantitative, and you can link the original record to the new classification to keep the basis for it.
On the other hand, if the raw output and mode information are gone, it is hard to say for sure what a stored 0 was converted from. Rather than calculating averages or distributions from such records as quantitative values, you can consider separating them as past records whose result type cannot be confirmed. When moving to a new format, compare with sample records how PASS, FAIL, quantitative readings, and results without readings each appear on screen and in files.
The point is not to fit every result into a single number. Only by preserving the test method, the device's raw output, the reading and unit, and the applied settings separately can you query screening PASS results and quantitative results in the same system without losing what each means.
