ISM Manufacturing release is published on the first business day of every month. ISM Non Manufacturing release is published on the third business day of the month. ISM indices compare the changes in various market areas on a month to month basis. The ISM index includes prices paid for all purchases including import purchases and purchases of food and energy excluding crude oil. The production index compares current month production with the prior month. The new orders index compares current month orders with the prior month. The backlog index compares current month unfilled orders with the prior month. The same is true for imports and exports. The inventory index compares current month units on hand with the prior month, not the dollar value. The employment index compares current month level of employment within purchasing companies with the prior month. The supplier deliveries index compares the current month rate at which orders are filled with the prior month. ISM has created an overall indicator for the non-manufacturing sector, and is a better indicator of the relationship to GDP than the Business Activity Index alone. The formula for the new NMI includes: Business Activity Index 25%, New Orders Index 25%, Employment Index 25%, Supplier Deliveries Index 25% Bloomberg News has calculated the index level retroactively based on this formula. The index levels do not come from ISM directly until Jan. 2008 data.