How does the EW of the Ca II H&K emission lines scale with logR'HK?

If I don't have to calculate the logR'HK, and instead can use the equivalent widths and scale, I'd rather do that! But do the two values actually correlate? To check, I first compared EW(Ca II K) for the stars in my sample with logR'HK for those with measured logR'HK in the literature.

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