TEMPERATURE READINGS VARIANCE

I have 4 different temperature gauges in my room and the only consistency that I have between them are the ones that are above the lights. They usually read 69-71 consistently. But, I have a few that I suspend in the room to hang above the girls that read differently. One, which I have from home depot (ya know the digital kind with the AA battery) will read 81-84 and the one that I have from the grow store (ya know the one that lives outside the room with the cord that goes into the room and suspends below the lights) will read 64-68. I don't get it. So I went and bought two more readers and they do the exact same thing. But my question is this, where should you measure for a true room temperature?

you want to be measuring air temperature and not radiant heat so the sensor should be within the air mass but shaded from the light, I keep mine in a white mesh bag hanging in the middle of canopy

I find too much inconsistency between different digital thermometers. Get yourself a nice old fashioned analog thermometer. If you're doing a good job at circulating the air in ur room then the only 2 things that should ever give you a false reading is radiant heat or a dodgy thermi