Fitbit is relatively accurate in terms of heart rate (I have a pulse oximeter and have been comparing). Spo2 is questionable however, but I don't have enough data to make a conclusive assessment.
However, your charts are atrocious and absolutely nonsensical. I have a graduate degree in quantitative research methods, so I am making an educated assessment here.
The spo2 variation chart makes absolutely no sense. Although only one y axis is identified (variation), there are obviously two y axes. What is that second y axis? What is considered 'high' variation vs 'low' variation? Without defined parameters, the line on that graph is absolutely meaningless. Is high variation 10%? 20%? 3%? I'm guessing maybe that secondary axis is actually the 'baseline' value? So if Fitbit determines my baseline spo2 during sleep is 96%, then a line starting at the bottom of 'low variation' might mean my spo2 has changed to 94 or 97? And then if the line goes up a bit further 10 minutes later, does it mean it has gone to 93 or 98? In short, what is the scale here? What are the parameters?
Secondly, the heart rate chart.... I am so disappointed in you guys! Like I said, the numbers seem relatively accurate. I have a heart condition so I need to follow trends pretty closely. But the chart... There aren't enough tick marks. On either the y or x axis. Right now, I can tell my heart rate was somewhere between 60 and 120 between midnight and noon (as an example). That is extremely unhelpful, not just for someone with a medical condition, but even for people who want to know for general fitness purposes. I understand one can scroll over the value to see the actual number, but it's very inefficient, and doesn't help when trying to get a bird's eye view of trends. Adding those extra ticks/ lines would not be difficult for you guys to do, and would increase the usefulness of your charts. exponentially.
I did do a quick search for the spo2 chart and couldn't find a straight answer anywhere... As for the heart rate chart, it's not really a question so much as a very strong suggestion. And yes, I fully understand Fitbits are not to be used as 'medical devices' (I've read the fine print). But even so, even for general purposes, those two charts really need some mending...
