S&P 500 vs. Advance-Decline analysis - Correction coming?

Did a basic analysis that looked at the pattern for the highs of the adv-decl (AD) at the week time frame. I then compared that to the S&P 500. You can see that starting around the end of June the AD has been showing lower highs. You can see the same pattern leading up to the other corrections in the S&P. The time between corrections is also in the correct time frame. Also note that the MACD is close to switching from positive to negative. The pattern seems to indicate that some form of correction is to be expected in the next week or two. However, the amount of correction is not something that can be determined from this analysis.