Bar Code Verifier Discrepancies: What Do They Mean?
A bar code verifier is a test device. Test devices are supposed to be reliable, which means their results are supposed to be repeatable across different brands and models. What does it mean when verifier results from Brand X are not the same as Brand Y? Which one should you believe?
It’s a big question, so let’s deconstruct it into reasonable parts.
Not all bar code verifiers are ANSI/ISO compliant. This can be challenging to discern from some of the “creative” language used by some verifier brands. Verifiers that are “designed to be ANSI/ISO compliant” are not compliant; verifiers that product a report “based on the ANSI/ISO specification” are not compliant. Verifiers that are independently tested and certified ANSI/ISO complaint are ANSI/ISO compliant.
How important is ANSI/ISO compliance in a test device? It certifies that the device performs to a known standard. Without ANSI/ISO certification it’s like a rubber ruler, optimistic today when Tom uses it, pessimistic tomorrow when Tom uses it again, sometimes (or never) just truthful. If you throw a third factor such as a user-influenced device like a wand scanner into the equation, and you can’t predict anything because Tom and Bob will always get different results on the same verifier testing the same bar code in the same QA lab within minutes of each other.
The conclusion here is that when two non-ANSI/ISO compliant verifiers of the same brand disagree, you cannot believe either of them. And results from ANSI/ISO compliant wand verifiers will vary due to human and ergonomic factors—there is no apples-to-apples comparability possible with them. Wands are so 1980’s.
This raises another concern because wands are the only way some verifier brand achieve ANSI/ISO compliance. One very popular brand, which has now been discontinued, came with a gun-type scanner that was not ANSI/ISO compliant because the variable distance and angle of the handheld scanner from the bar code made it impossible to test contrast and reflectivity. The manufacturer’s solution was to offer optional, extra-cost wands which could test contrast and reflectivity but had all the inherent problems discussed above. Not a great solution.
What about gun-scanners that are fixture into a stand that locks the angle and distance? One brand does that with a repurposed PDT and claims that it provides “ANSI and Traditional Grading” and requires “No Daily Calibration.” Can you guess why?
Which verifier should you trust when verifier Brand X and Brand Y disagree? Eliminate the non-ANSI/ISO compliant brand; eliminate the wand-based verifier. If both units are ANSI/ISO compliant and neither use a wand, re-calibrate them both and re-test your bar code. If the results still vary, make sure ambient room lighting is not strong, especially an adjacent window or other sources of strong side-lighting. Also inspect the verifiers for dust, dirt, scratches or cracks on the scan window and any damage to cables and connectors.
If everything checks out but the verifiers still disagree, have them tested using a GS1 Calibrated Certified Standard Test Card (CCSTC).
Note: get the CCSTC for the symbology (type of bar code) you intend to verify.
In conclusion, it makes no sense to buy a Brand X verifier because your customer or vendor also has one. ANSI/ISO compliant verifiers will often grade a bar code lower than a non-compliant verifier because they are testing the full range of quality parameters, and they are testing more accurately. Under no circumstances default to the verifier that gives the better grade. Would you do that with your oncologist?