If you want to get an objective picture of the performance of your Telraam S2 unit on your street, then follow our example below which will illustrate how to calculate accuracy values and compare them with our expectations.
Let’s take an example:
Cars on the 24-hour screen of your Telraam S2 just before starting the 15 minute validation count: 2548
Your validation count for cars: 145
Cars on the 24-hour screen of your Telraam S2 just after finishing the 15 minute validation count: 2683
How the calculation works:
Calculate the counts your Telraam S2 saw during your validation.
Our example: 2683-2548=135Accept your validation count as the ground truth
Our example: 145Calculate the relative observed error of Telraam S2 compared to the ground truth with the formula: Error_o [%] = |Counts Telraam S2 - Ground truth|/(Ground truth/100%)
Our example: Error_o [%] = |135-145|/(145/100%) = |-10|/(1.45/1%) = 10%/1.45 = 6.9%Look up the maximum error for the selected mode that we consider acceptable for each of the modes from the table below.
Our example: Error_m [%] = 10%
Mode | Acceptable accuracy | Acceptable error (error_m) |
|---|---|---|
75% | 25% | |
80% | 20% | |
90% | 10% | |
85% | 15% |
Comparing the observed error to the maximum acceptable error, there are two possible outcomes:
Error_o > Error_m:
If the observed error is greater than the maximum acceptable error, that means that your Telraam S2 is performing below our expectations. In this case we definitely encourage you to carry out a Video validation, so we can improve Telraam S2 and understand why your device is performing as it is performing.
Error_m ≥ Error_o:
If the observed error is less than (or equal to) the maximum acceptable error, that means that your Telraam S2 is performing as expected.
Our example 10% ≥ 6.9%
You can do this exercise for each of the 4 modes, and if any of them shows results outside of the expected range, we ask you to perform a Video validation. Otherwise you should simply submit the data from your Quick validation.
