It's like any other data stream; the higher the resolution of your analysis the more scattering you see. Trends are more important then the day to day (or hour to hour, or minute to minute) numbers. For the last month or so, the trending has been upward, which is the opposite direction from where we want it to go. There also may be some day to day variability in the availability of testing. For example, if testing is less available on the weekend and they take 3-4 days to report results, there could be a dip in reported cases later in the week because of it. Of course, that is pure conjecture an my part...