The data fields used to describe Usage, Fulfillment (including Open Access), and Subscription and ILL costs are included here.  The numbers are annual average percentages from our projections of the next five years.  More details on projection approach is available in this preprint.


Because APC costs are calculated on a slightly different set of journals (hybrid and gold OA journals), they are described separately, here.


Key Stats

(most of the Key Stats are also included in their related sections below)


Net cost per paid use (NCPPU)

NCPPU is the net cost (subscription minus ILL), divided by Paid Use (Usage that can't be met with free sources). This is our most important measure of journal value--it summarizes the real value you're getting for your subscription dollar. Read more about NCPPU here.


Rank of Net cost per paid use (NCPPU)

The journal's rank according to Net cost per paid use (NCPPU), relative to other journals in this dataset.  The most cost-effective journal has a rank of 1.


Cost

The cost of this journal according to the Settings and Subscription status of the journals in this Scenario.  It will be either Subscription Cost or ILL Cost (see next columns), depending on whether the journal is currently subscribed to or not in this scenario.


Usage

The projected Usage of the journal by your institution.  Usage is a measure of the journal's value to your institution.  It is calculated as:

Usage of a journal = Downloads from the journal
                + (Citations to the journal by your authors) * (citation weight)
                + (Authored papers in the journal) * (authorship weight)


Instant Usage Percentage

The percent of Usage that is available instantly -- available as Open Access, Backfile, ASNs, or Subscription.  Or to look at it the other way, all Usage that isn't via ILL or Other (delayed)


Free Instant Usage Percentage

The percent of Usage that can be met by instantly-available, free sources: Open Access, Backfile, and ASNs. This excludes usage met only by ILL, 'Other (delayed),' or Subscription.


Costs

Net cost per paid use

NCPPU is the net cost (subscription minus ILL), divided by Paid Use (Usage that can't be met with free sources). This is our most important measure of journal value--it summarizes the real value you're getting for your subscription dollar. Read more about NCPPU here.


Cost

The cost of this journal according to the Settings and Subscription status of the journals in this Scenario.  It will be either Subscription Cost or ILL Cost (see next columns), depending on whether the journal is currently subscribed to or not in this scenario.


Subscription Cost

The ala carte subscription cost of this journal.  It includes a 'content fee' based on your settings, and annual price increases over the next five years (the cost shown is the average cost over the next five years).  This data is based on public price lists unless you've uploaded a custom price list (available in a purchased account).


ILL Cost

The ILL subscription cost of this journal.  It is based on the ILL transaction cost from the settings, and an ILL request rate (adjustable in the settings, though the default is based on an extensive literature search of other institution's experiences). 


Subscription minus ILL Cost

The net cost of the subscription, which is the Subscription cost above minus the ILL cost (since almost all universities will offer a journal by ILL if they didn't subscribe).  For some journals with very high Usage and low subscription prices this number is actually negative -- subscribing is *cheaper* than filling all the anticipated ILL requests.



Open Access


Percent of Usage that is OA

The percent of Usage that is available as Green, Hybrid, or Bronze Open Access.


Percent of Usage that is Green OA

The percent of Usage that is available as Green OA.  This is Open Access hosted on open repositories, like Harvard's institutional repository, arXiv, or PMC.  Green OA that hasn't been peer-reviewed (preprints, submitted drafts, etc) can be excluded in Settings.


Percent of Usage that is Hybrid OA

The percent of Usage that is available as Hybrid OA.  This is Open Access hosted on the publisher site with an open license in an otherwise subscription journal.  Usually an APC was paid by the authors when they published this paper.  


Percent of Usage that is Bronze OA

The percent of Usage that is available as Bronze OA.  This is Open Access hosted on the publisher site in an otherwise subscription journal, but unlike Hybrid it does not have an open license.  It is sometimes promotional material, and sometimes open after an embargo in a Delayed OA journal (like Elsevier's Open Archive content).  Bronze OA can be excluded in Settings.


Percent of Usage that is Peer-reviewed OA

Percent of Usage that is the peer-reviewed version.  This includes all of Hybrid and Bronze, and the portion of Green OA that is an Accepted or Published version of the paper.  Green OA that hasn't been peer-reviewed (preprints, submitted drafts, etc) can be excluded in Settings.



Fulfillment


ASNs

The percent of Usage that is available from Academic Social Networks like ResearchGate and Academia.edu.  These are not considered open repositories, so papers hosted here are not considered Open Access.  These can be excluded in the settings.


Open Access

The percent of Usage that is available as Green, Hybrid, or Bronze Open Access.  Some of this content can be excluded in the settings (see the Open Access page for more info).


Backfile

The percent of Usage that is available from your backfile -- the content that you still have access to because it was published while you had a subscription.  If your institution doesn't have Perpetual access you can exclude Backfile in the settings. In a Paid Account you can also upload a customized list of perpetual access availability by journal.


Subscription

Percent of Usage that is fulfilled via subscription in this scenario.  Of course if you've subscribed to a journal you can actually fulfill all of it via subscription, but we model that you fulfill via free, instant sources when possible, and only subscription for the remainder of the paywalled content (costs and instant percentages aren't affected by this decision, it mostly just shows up in the fulfillment bar graphs showing fulfillment breakdowns).


ILL

Percent of Usage that is fulfilled via ILL in this scenario.  This all Usage that isn't available via a free, instant route multiplied by the ILL request rate (adjustable in the settings, though the default is based on an extensive literature search of other institution's experiences).


Other (delayed)

Percent of Usage that is fulfilled via Other (delayed) paths in this scenario.  This all Usage that isn't available via a free, instant route and the researcher does not choose to place an ILL request, but instead fulfills their information need another way -- asks the author for a paper, asks a colleague, finds another similar paper that is good enough for their purposes, etc.


Impact


Usage

The projected Usage of the journal by your institution.  Usage is a measure of the journal's value to your institution.  It is calculated as:

Usage of a journal = Downloads from the journal
                + (Citations to the journal by your authors) * (citation weight)
                + (Authored papers in the journal) * (authorship weight)


Downloads

The number of times people in your institution will download papers from this journal.  We base this on your COUNTER statistics and literature on download decay curves (how often an article is to be downloaded based on how long ago it was published).


Citations to papers

The number of times that a paper authored by someone in your institution will cite a paper in this journal.  This number is based on the citations patterns of the previous five years.  The importance of this number to overall Usage is determined by the Citation Weight setting.


Authored papers

The number of papers in this journal that have at least one author from your institution.  This number is based on the authorship patterns of the previous five years.  The importance of this number to overall Usage is determined by the Authorship Weight setting.