Overview Each year, our scholarly market sizing update and analysis goes way beyond open access headlines. One consistent finding is that market share of open and subscription access is highly dependent on subject area. This month we look at how to best use our Delta Think Data and Analytics Tool (DAT) to understand and analyze these variations. With coverage of approximately 220 detailed subject areas, the data shows that headlines can sometimes mask important detail. Background Since we began our scholarly journal market analyses in 2017, one of our core objectives has been to enable deep analysis of our headline findings. Our annual market share updates represent a summing of data – more than 200 detailed subject areas, 200 or so countries, also split by society vs. non-society journal ownership. This level of detail is clearly too much for our monthly short-form analyses, so we present the market-wide headlines in our annual updates. However, by picking one subject area as an example, we can see how much nuance lies beneath the surface, and why these variations matter. Subscribers to DAT can use our interactive tools to quickly and easily see each level of detail and filter for just those relevant to their organization. Market Share Variation by Subject Area Our latest market headlines suggested that open access (OA) accounted for just under 50% of article output in 2024. However, this headline proportion varies considerably by subject area.