Impact Metrics

This platform has had a profound influence on our field. I hope that everyone will continue to contribute to this platform and replace these high-cost textbooks.

Calculating the actual impact of a resource like this is difficult, because to be accurate you would have to factor in benefits to students, benefits to instructors, relative advantage of the resources to alternatives, and so forth.

To get a general sense of impacts as perceived value of our content, we rely upon reader feedback on the overall quality of each chapter.

To get a general sense of impacts as cost savings, though, we can also look at two different factors: (1) reported course adoptions (for a low-end estimate) and (2) website activity metrics (for a high-end estimate). Actual cost savings will likely fall somewhere between the two.

And finally, to get a sense for the impact that these cost savings have on students, we can calculate effects in terms of food, healthcare, and tuition benefits based on average rates.

Reader Feedback

Each chapter in our platform has a default end-of-chapter survey to allow readers to provide a quality rating on the chapter. These ratings allow us to see how readers perceive the quality of our content overall.

Average chapter rating 4.2/5.0 "High Quality" out of 28,342 ratings

Reported Course Adoptions

One extremely conservative way to estimate cost savings to students can be done by calculating textbook adoptions by specific courses over time. This represents the bare minimum of cost savings to students, though the actual amount is likely much higher due to adoptions that are not reported.

The following table provides details for courses that have reported their textbook adoptions to us.

Website Activity

The limitation of relying solely upon course adoptions is that many courses and informal learners throughout the world may use the resource without reporting their use.

To remedy this, as a simple, broader metric we can count things like PDF downloads and page views and determine the cost savings to learners based upon the current market value of similar commercial products.

To provide a conservative estimate, we will assume the following:

• A PDF download of an entire textbook would be similar to purchasing a similar commercial textbook. Commercial textbooks in this realm range anywhere from $30 to $150 (with an average of $90), but we will go with a low average estimate of $50 per book download.
• A PDF download of a textbook chapter would be similar to purchasing a single chapter or a portion of a textbook. For instance, commercial research articles generally cost anywhere from $10 to $45 for a single PDF download. For each chapter, we will calculate its PDF downloads as a percent of the overall book cost (e.g., if there are 10 chapters in the book, then each chapter download would only count as $5). We will also ignore any chapters with fewer than 50 words from this calculation.
• Content-wise, the value of a web view is identical to that of a chapter PDF download. Because we collect analytics data on consenting users, we can track how long users spend on a chapter page that they are viewing. Operating on a range of projected adult reading speeds from 150-300 words per minute mapped (inversely) across a Flesch-Kincaid reading difficulty scale of 0-100, we can determine whether tracked users spent enough time on any given chapter to have read it (based upon the chapter's word count, Flesch-Kincaid difficulty, and a 70% threshold value). For instance, if a chapter had 5,000 words and (based on the sentence complexity) it was estimated that adult readers should take 20 minutes to read it at 250 words per minute, then only readers who spent at least 14 minutes on the page would be counted as a read. The cost savings of each read would be calculated in the same way as a chapter PDF download.
• Finally, many users choose not to allow us to track their viewing activities, but we can still see that the chapter was opened. Using the reading likelihood of the chapter determinable by the previous step (total tracked page views / predicted reads), we can also predict the number of non-tracked users who read the page by multiplying the reading likelihood by the number of total (untracked) page views. For instance, if it was determined in the previous step that 15% of tracked users who viewed a chapter in a book spent sufficient time on the page to have read it, then we would count this same percentage of untracked page views as reads, calculating cost savings for the chapter similar to previous steps.

Given the historical activity of the site over the past 45 months, here is the estimated cost impact to learners based upon web activity:

Student Benefits

And finally, decontextualized numbers mean little as disconnected from day-to-day impacts on students' lives. For this reason, many studies on effects of open textbooks on students consider how cost savings benefit students' lives in terms of health, wellbeing, grades, course completion, and so forth.

Because our site does not track individual users, we cannot predict cost savings for each user, but we can translate overall cost savings in terms of equivalent student benefits on things like food, healthcare, tuition credits, and so forth.

In this way, we can envision the actual impacts of our students' cost savings by realizing that this equals the following: