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 tier assignment for each institution we computed:

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

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

Last Updated: October 19, 2011