Unfortunately you are going to be massively disappointed.
There is going to be a massive variation of runtime, light output and reliability.
The things that will cause problems:
- Quality of manufacture - The runtime, light output and reliability will vary wildly depending on the manufacture and country.
- Size and shape of the stick - There is about 5 common shapes & sizes available that will affect the light output and duration
- Age (from date of manufacture) - Glow sticks degrade over time causing shorter run times/light output
- Packaging - Light and air intrusion can degrade the chemicals causing shorter run times/light output
- Temperature - Glow sticks stored in higher temps will degrade faster and will accelerate the chemical reaction causing shorter run times, colder temps will impede the reaction greatly reducing the light output.
- Storage - How they are stored is going to affect how reliable they are (rough handling can crack the glass vial &/or cause the stick to leak)
- Colour - Each of the different colour variations will have different light outputs.
- Stated runtime - Sticks commonly come in 4/6/12 hour versions (other duration available) shorter run times will be brighter but the longer runtime sticks will be less bright.
So to do tests you would be needing to test thousands of glow sticks at minimum to get anything close to reliable numbers.