Computation of AIP tiers

To establish tiers for institutional prices, AIP has developed a methodology applicable worldwide to reflect the level of research activity at an institution. We restrict the research activity to physics and use only data that we can measure directly, such as online activity, number of papers published in AIP journals, and subscriptions. The resulting procedure is therefore purely mathematical, based on readily measurable numerical values. The procedure is as follows:

For the assignment of 2007 and 2008 tiers, for each institution we computed:

D = average online activity for 2004 and 2005 (i.e., downloads of full text articles)
P = average number of articles by institution’s authors published in AIP journals in 2004 and 2005
S = average number of subscriptions to AIP journals in 2004 and 2005

Each institution’s "AIP Activity Index" (A) was evaluated based on these values using a formula that combines them with weighting factors and the medians of D, P, and S for all institutions:

A = D/490 + P/6.1 + S/3

Based on the computed activity, we set tier ranges for A so that the resulting tier assignments most closely match prior years’ overall statistics (with original ranges evaluated with consideration of Carnegie tiers for North American institutions), but with an expansion to six tiers to allow for smaller price differences between adjacent tiers among the higher tiers. These ranges are:

Tier 6:			A	>	120
Tier 5:	120	>	A	>	40
Tier 4:	40	>	A	>	13.0
Tier 3:	13.0	>	A	>	4.4
Tier 2:	4.4	>	A	>	1.3
Tier 1:	1.3	>	A

These thresholds are then applied to determine tiers for all institutions worldwide. The tiers assigned to an institution in this way will then affect the price of any or all subscriptions for AIP Archival journals. As an overall result, the distribution of institutions among the six tiers is:

		Median activity A in each tier
Tier 6:	0.3%	160
Tier 5:	3.3%	71
Tier 4:	13%	23
Tier 3:	17%	8.7
Tier 2:	27%	2.7
Tier 1:	39%	0.7

The tiered subscription prices apply to online-only, quarterly CD-ROM plus online, and single-copy print plus online subscriptions; multiple print copies are offered at a substantial discount.

Last Updated: July 2, 2008