Clarify meaning of "improves correlations" in "correlate signals" vignette #371
Description
In the "lagged correlations" section of the "correlate signals" vignette, the meaning of "improves" is unclear in
lagging the case rates back by 10 days improves the correlations
Change wording to "higher" or "large positive", etc, to be more clear. "Higher" might be misinterpreted as "more extreme", but "higher positive" might be misinterpreted as only applying to already-positive correlations on the graph.