Although substantial efforts have been made in this area, it is still far from ideal because many series have only recently started to be collected. Also, the process of collecting and constructing regional time series is time consuming and costly. Nevertheless, the index was constructed with the best time series available and will be revised as longer series become available. The most important criterion used to choose the components of the index was the economic importance of each series. The main indicator for this sector is still gross gaming revenues.
Construction is represented by residential and commercial building permits.
Because building permits can be misleading in terms of numbers, the valuation of those permits is also included in the index. The internal market is also represented by the value of taxable sales. The third criterion is timing. This criterion was adapted for the regional data characteristics and measures how well the series led, coincided, or lagged the actual fluctuation of the economy. A good measure of regional business cycles is not available since data on the gross state product is associated with many empirical problems.