There was also another post in regards to difference in the NASI calculated from the data link above and the NASI values found at stockcharts.com. When backtested, the system had a noticeable difference in returns when different data sources were used (adv/dec link vs. Stockcharts.com). The problem here is that there is only 2 years worth of data at stockcharts.com. If someone has this data, prehaps they can do a comparison between the two sets of data to verify if there is a problem.
SI formula: I think the one that everyone is using is as follows:
When I set up the data in the sheet, I used the dates from historical data download from Decision Point to filter/sync everything to. Some of their dates on major holidays were off by 1 day from the other source. Everything was adjusted to their dates.
If you can provide another source of the data needed, please plug it in and share with all.