Markit US Services PMI (Purchasing Managers' Index) is based on data collected from a representative panel of over 400 private sector companies covering transport and communication, financial intermediaries, business and personal services, computing & IT and hotels and restaurants. The index tracks variables such as sales, employment, inventories and prices. A reading above 50 indicates that the services sector is generally expanding; below 50 indicates that it is generally declining.
A higher than expected figure should be seen as positive (bullish) for the USD while a lower than expected figure should be seen as negative (bearish) for the USD.