The difficulty with Advance/Decline studies is different sources use a different number of stocks even though it is fo the same exchange. This was discussed with NH/NL calculations. WSJ has different numbers than Barchart that is different from other sources.

Using GTR1 and the following steps:

excd.a = 1
styp.a = 10!11!18!48
dspo(1) >= 1
trp(1,1)<0 (<0for decline, >0 for advance)

and using the count feature there have been 102 times when the sum of the last 10 day advances divided by the sum of the last 10 day declines exceed 2. Seventy occurred from 19441231 onwards.

Returns 19260114 to Present A/D >2

1 mth 3 mth 6 mth 12 mth
Median 1.04 1.07 1.13 1.15
Average 1.05 1.07 1.11 1.18
Min 0.91 0.78 0.71 0.77
Max 1.46 1.55 1.38 1.94

1926014 to 19441231 A/D>2

1 mth 3 mth 6 mth 12 mth
Median 1.05 1.02 1.06 1.02
Average 1.08 1.04 1.03 1.12

19450101 to Present A/D>2

1 mth 3 mth 6 mth 12 mth
Median 1.04 1.09 1.13 1.19
Average 1.04 1.08 1.15 1.21

Returns 19260114 to present
ignoring A/D ratio
1 mth 3 mth 6 mth 12 mth
Median 1.01 1.03 1.07 1.13
Average 1.01 1.03 1.06 1.12