Hi Stacy, I think the 97.8 temp is more accurate. If you use the temp corrector, what is the new temp that it gives you, is it as high as 98.5? Any waking activities will give a higher temperature, that's why high temp is easier to be inaccurate. Its harder to make a mistake with a low temp, unless you sleep in a colder than normal place, or if you didn't place the thermometer in your mouth correctly.
So, whenever I take a few temps, I usually take the lower temp, unless the high temp turns up more frequently. Does that make sense? heheh, I'm still new to charting, just giving my 2 cents since no one replied to your post.