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It is difficult for a student to succeed in a course without access to course materials and assignments; and yet, some students delay up to a month in obtaining access to these essential materials. Students delay buying material required for their course due to multiple reasons. Out of a concern for students with limited financial resources, some publishers offer a period of free courtesy access. But this may lead to students having access later in the course but then having a lapsed period until they pay for the materials after the courtesy access period ends. Not having key course materials early on probably hurts learning, but how much? In this paper, we investigate the question, "Does lack of access to instructional material impact student performance in blended learning courses?" Specifically, we analyze students who purchased and obtained access to online content at different points in the course. We determine that both types of failure to obtain access to course materials (delaying in signing up for the product, or signing up for a free trial and letting the trial period lapse without purchasing the materials) are associated with substantially worse student outcomes. Students who purchased the product within the first few days of class had the best scores (median 77). Those who waited two weeks before accessing the product did the worst (median 56, effect size Cliff's Delta=0.31 1). We conclude with a discussion of possible interventions and actions that can be taken to ameliorate the situation.

- Information systems → Data mining;

- Applied com- puting → Education; E-learning;

^{1}For Cliff's Delta a small effect size is around 0.147, a
medium effect size around 0.33, and a large effect size around
0.474.

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DOI: 10.475/123_4

effect size, procrastination, content adoption delay, performance

There is evidence that students benefit when they start
their work early rather than waiting to start or procrastinating
[4, 6]. However, despite the evidence for benefits
from getting a prompt start to a course, there is emerging
evidence that many learners do not even purchase their
course materials until one or even two weeks after the course
has started. In this paper, we study the impact of this student
choice on course outcomes, and propose interventions
that may have the potential to reduce negative outcomes
stemming from this choice.

More specifically, in this paper, we investigate the question
'Does lack of access to textbooks and digital instruction
resource significantly affect learning performance?' Students
delay getting access to material required for their course for
all sorts of reasons. Not having key course materials early
on probably hurts learning, but how much? There are multiple
reasons to look into this question: Many instructors
believe that it has an effect when a student delays getting
the materials required for their course. But how much do
their grades suffer? And how long can a student delay on
this before there is a detrimental effect? And if it does
impact outcomes, what interventions can we apply in order
to insure that student indeed do get access to material in a
timely fashion? We will discuss some ways that it may be
possible to intervene and address the issue.

There are multiple reasons why students may delay in purchasing their course materials. For some students it may simply be procrastination [10]. 87% of the 13,000 high school and college students surveyed by StudyMode.com admitted to procrastinating. 45% of students surveyed reported that they believe that their procrastination negatively impacts their grades on at least a fairly regular basis. Other students may be trying to decide what course to take. For some students, it simply comes down to the fact that they do not receive their financial aid check until two weeks in the semester, and they can not afford to buy materials before then. Research has shown that even opening the text book prior to the start of course is predictive of success in the course [4].

Agnihotri and Ott also determined that another form of
procrastination, late registration, is associated with lower
fall-to-fall student retention [2]. In addition, Levy and Rahm
[8] found that students who procrastinated performed significantly
worse than those who completed their work in a more
timely fashion. Results of this study indicate that when it
comes to online exams, over half (58%) of the students tend
to procrastinate, while the rest (42%) started the exam well
before the deadline and avoided procrastination.

Jayaprakash et al., determined that course success can be
predicted from the student's interaction with the learning
management system [7]. Predictive models have also been
developed by Civitas and deployed at a range of institutions
[9]. Their predictive models were able to identify with 83%
accuracy on the first day of a course the students who would
successfully complete a course based on ACT scores, SAT
scores and economic factors.

In order to estimate the impact of student choice about
when to obtain access to content, and when students purchase
access to content, we look at the differences between
different groups of students. Specifically, we differentiated
groups of students from each other in terms of how long they
chose to go without access to course materials.

We study this in the context of the Connect system [1].
Connect is an open learning environment for students and
instructors in the higher education market. In this analysis,
we examine this utilized about 2.6 million students who
used Connect in 2015. These students were in 145,115 course
sections taught by 14,000 instructors, who created 89 million
assignments using about 2000 textbooks/course material
packets. The majority (75%) of the students who obtain
access to Connect purchase access outright. However, there
is an option for students to try it for free for two weeks
(termed Courtesy Access) and then convert it to full access
at a later date. Of the students who opt for Courtesy Access,
80% convert to full access.

For all the students we obtained data about when they got
access to Connect. Additionally we obtained the start date
of the class. We use this information to compute two variables:
Start delay is defined as how many days after the
start of the course the student first obtained access to the
online content, whether by purchasing the course or obtaining
courtesy access. Conversion delay, defined only for those
students who obtained courtesy access and then eventually
purchased access, is the number of days between when their
courtesy access period started and when they converted to
full access. Since the courtesy access period is two weeks,
students with a conversion delay of two weeks or less have a
conversion delay of zero. We also obtained data on students'
assignment scores and quiz scores, and computed their final
scores for the class based on this data. We compute these
scores in two ways. The first, termed "ScoreCompleted", is a
strict average of all the scores students have received on the
assignments/quizzes etc. that they submitted. The second
one, termed "ScoreAll", shows the score with the impact of
missed assignments factored in. In other words, if a student
failed to do two assignments due to not having the materials
for two weeks, "ScoreAll" will directly penalize them but
"ScoreCompleted" will not.

A quick analysis of our data showed that these variables
were largely non-normal. As such, we compared the scores

Figure 1: Histogram of aquiring access relative to start of semester.

of students who obtain access of the book at different points using the Cliff's Delta effect size measure [5]. The Cliff's Delta statistic is a non-parametric effect size measure that quantifies the amount of difference between two groups of observations. This effect size measure is used for non-normal distributions; an analogue for normal distributions is Cohen's D. Cliff's Delta was chosen for its particularly high robustness to unusual data distributions; other alternatives such as Algina's D control for outliers but not for bimodality or extremely high skew.

Our data set consisted of:

- 2.6 million students in 145,115 sections in 2015, who made a total 3.2 million purchases
- 2.4 million (75%) outright purchases (i.e. without first signing up for a Courtesy Access period)
- 818k (25%) Courtesy Access trials: 633k (77% of 818k) purchases after trial, 185k (23% of 818k) trials without purchases

Figures 1 and 2 show the histogram of getting access to the
course material relative to the start of the semester (start
delay on the X axis vs. counts on the Y axis) and the conversions
relative to the start of courtesy access (conversion
delay on the X axis vs. counts on the Y axis). We track up
to 30 days after the start of courtesy access in our data. 47%
of the student get access to content (full or courtesy access)
in the first 4 days of the semester. Another 38% happens
between the 5th-12th days and finally 14% occur 12 or more
days after the semester starts. Very few students obtain
access to course materials prior to the official start date of
the course, a contrast to the results presented in [4]. This
is largely because the way the courses are set up; students
typically receive the link to obtain course materials on the
rst day of class from the instructor.

In terms of conversions from Courtesy Access to full (paid)
access, 54.0% of conversions happen in less than 14 days, a
time window where the student has no lapse in their access
to content. Another 20.0% conversions happen in 14-16
days, suggesting fairly limited time lapse and fairly limited
disruption to the student's studies. In fact, 14 days is the

Figure 2: Histogram of conversion dates relative to start of Courtesy Access.

Figure 3: ScoreCompleted and ScoreAll relative to start of semester.

modal day for conversion. However, a sizable 26.0% of conversions
happen after 16 days of the start of Courtesy Access.
And 7% of conversions occur more than 21 days after
the start of Courtesy Access, indicating that the student is
without access for the whole week (see Figure 2).

Figures 3 and 4 show the student assignment/quiz scores
relative to the two delays we have talked about. In each
figure, the first plot shows the ScoreCompleted vs. the time
delay and the second one shows the ScoreAll which considers
the missed assignments as well. The graphs in figure 3 show
that performance on the completed assignments (ScoreCompleted)
drops a bit for students who delay in getting access
once the semester starts. Figure 4 shows the same but
with respect to getting full access (conversion delay) to the
product after starting free courtesy access. A student who
obtains access on the rst day of the course and immediately
purchases access will have an median ScoreCompleted
of 89%. By contrast, a student who waits 14 days to obtain
access will have a median ScoreCompleted of 84%. The
ScoreAll for students who get access on the first day of the
class is 81%. A student who waits 14 days to obtain access
will have an average ScoreAll of 67.5%, and a student
who waits a full week or more to convert to full accesss after
their 2-week Courtesy Access period ends (i.e. 21 days after
obtaining Courtesy Access) will have an average ScoreAll of
64%.

These results suggest that students who choose (for whatever
reason) to not have access to course materials for a

Figure 4: ScoreCompleted and ScoreAll relative to the start of the Courtesy Access.

period of time have worse outcomes, but that much of this
difference (81% to 67%) is due to missing assignments rather
than worse performance on the assignments they complete.
This is reassuring, because it suggests that encouraging students
to purchase or obtain their materials in a timely fashion
has the potential to ameliorate the missed assignments
problem, providing students with a chance to perform better
in the course (and learn all the material). Of course,
encouraging students to purchase or obtain their materials
in a timely fashion will not benefit all students; for example,
students who cease participation in the course for a
week due to a personal or family emergency are unlikely to
be benefitted. But positive impact may be possible for the
students who fail to purchase or obtain their materials due
to simple procrastination [6, 8]. After all, no matter how
bright a student is, he or she cannot successfully complete
an assignment that he or she does not have access to.

Of course, many of the students who have a start delay will
also have a purchase delay. The same factors that lead to one
may lead to the other. The relationship between start delay
and conversion delay, and the associated scores, are shown in
figure 5. The x-axis shows the start delay for getting access
to the online content. The y-axis shows the conversion delay,
the time the student delayed between obtaining Courtesy
Access and purchasing full access. The size of the circle
indicates the number of people in that group. The color
indicates the median score of the students in that cohort.
As can be seen, students have relatively better scores when
the start delay is less than 4 days and the conversion delay is
less than 14 days. When the start delay or conversion delay
go above these numbers, the student is likely to obtain a
lower score.

In order to quantify the effects of start delay and conversion delay after signing up for courtesy access, we computed Cliff's Delta effect sizes on ScoreAll between groups of students who delayed for different amounts of time. Cliff's delta or d [5] is a measure of how often one the values in one distribution are larger than the values in a second distribution. Crucially, it is non-parametric and does not require any assumptions about the shape or spread of the two distributions. The sample estimate d is given by:

Figure 5: Heat map of scores for different start and purchase delays.

where the two distributions are of size n and m with items
xi and xj , respectively, and # is defined as the number of
times. d is linearly related to the Mann-Whitney U statistic,
however it captures the direction of the difference in its sign
which is important to us in this study. Cliff's delta ranges
from +1 when all the values in one group are higher than the
values of the other group, in the expected directionand -1
when the reverse is true. Two completely overlapping distributions
will have a Cliff's delta of 0. Cliïň Ă^aĂŹs delta evaluates
the degree of overlapping between two vectors of observations.
A less raw interpretation, is to use conventional
descriptors like Cohen's d (small, medium, large), which are
explicitly conventional according to Cohen. For Cliff's Delta
absolute value you have a small effect size around 0.15, a
medium effect size around 0.33, and a large effect size around
0.50.

We computed the Cliff's delta for each of the combinations
of the start delay and conversion delay. More specifically, for
the start delay, we computed Cliff's delta measure for all the
students scores with start delay less than or equal to a vs.
start delay greater than a, where a takes values from 2 to
25. So in the above equation, we set xi to be student scores
whose start delay is less than or equal to a and xj is the
student scores for the rest of the students. We then found
the start delay, a that resulted in the maximum Cliff's delta.
Also, we computed the effect size for students with start delay
less than or equal to a vs. students with start delay
greater than b, where b takes all possible values from a to
25. So in the above equation, we set xi to be student scores
whose start delay is less than or equal to a and xj is the student
scores for students with start delay greater than b. We
repeated the procedure for delay in converting to full access
after obtaining 2 week courtesy access, as well. We want
to find automatic cutoff points where there was maximum
impact on the students' scores. We finally repeated the procedure
with different combinations of start and conversion
delays. To get the results we ran about 4000 different combinations
of different start and conversion times to get all
the different Cliff's delta.

- For students with start delay less than or equal to 12 days, the median score is 74.4% vs. students with a start delay of more than 12 days, the median score was 62.7%. Cliff's delta was 0.17.
- For students with start delay less than 3 days, the median score is 76.7% vs. students with a start delay of more than 12 days, the median score was 62.7%. Cliff's delta was 0.20.

Figure 6: Score distributions of students with start delay less than 3 days and conversion delay less than 15 days.

Figure 7: Score distributions of students with start delay greater than 15 days and conversion delay greater than 23 days.

- For students with conversion delay less than 19 days, the median score is 73.5% vs. students with a conversion delay of 19 days or more, the median score was 63.9%. Cliff's delta was 0.14.
- For students with conversion delay less than 16, the median score is 73.6% vs. conversion delay greater than 22, the median score was 60.4%. Cliff's delta was 0.19.

We then found automatic cut-offs for combinations of both the start delay and conversion delay:

- The Cliff's delta students with start delay less than 3 days and conversion delay less than 23 days (Median score 76.9%) vs. all other students (Median score 60.3%) is 0.25
- For varying start and conversion delays, students with start delay less than 3 days and conversion delay less than 15 days do much better (Median score 77.3%) than students who get access 15 days of the start of the semester and have a conversion time greater than 23 days (Median score 56.4%). Cliff's delta is 0.31.

Overall, then, the students who have the highest performance in their courses access the course materials within

the first few days after the start of the class. If they opt for the free courtesy access, then they are more successful if they convert to full access before they lose access to content. The worst choice is to wait for two weeks or more to obtain access to content and then let the courtesy access lapse for a week or more before converting to full access. Figures 6 and 7 show the distribution of scores for these two extremes. The odds ratio of the second group getting a score less than 60 is 2.44 and the risk ratio of getting this score and possibly failing the course is 1.68.

While our results are correlational, they nonetheless show
large differences in student outcomes based on when students
access course materials. These findings therefore warrant
intervention studies that can both validate whether
these findings are causal, while testing interventions that
may be able to improve student outcomes. The findings
presented here suggest that there is the opportunity for improving
student outcomes if we can convince students to
access course materials from the beginning, and to avoid
lapses in access.

One clear intervention is to simply give free access to every
student. Unfortunately, as the Connect product team and
project researchers need to earn money in order to eat, this
solution is probably infeasible. However, to the extent that
some failure to purchase course materials is due to student
economic situations, such as delays in students receiving - financial aid (students also need to eat), it may be possible
for universities to arrange support for their students so that
they can purchase materials on time. The two-week Courtesy
Access period was originally designed with this in mind,
but does not seem to be sufficient.

A related intervention, sometimes termed "inclusive access",
is to set up a university-wide program to automatically
provide all students with courtesy access to the online
content at the beginning of class. If they drop the course,
the content is not charged. This will help students who
tend to procrastinate get access to content and facilitates
coordination at the university level between when the student
receives financial aid and when they are charged for the
course materials.

Where this type of program is infeasible, other solutions
may help students who delay in obtaining or purchasing access
due to reasons such as procrastination. One approach
is to work with instructors to emphasize to students the
importance of getting access to the course material from
the beginning. For example, it may be possible to create
infographics that can be shared with instructors showing
them the impact of delays in students obtaining access to
content. Another potentially useful approach may be to
nudge students to buy the product when the courtesy access
lapses. Previous work has shown the benefits obtained
from instructors sending email messages to students at risk
of poorer performance, explaining why they are at risk [3].

These findings indicate that it is important for students to get going quickly and avoid delay. Getting off to a fast start seems to be important for student success. One limitation to our findings, however, is that they are correlational

rather than causal. Investigating the degree to which these findings are causal, through an experimental study, will be
an important step for future work.

What can we do to improve outcomes? It may be valuable
to set up inclusive access, where students have free trials that
last until they can be expected to receive financial aid checks.
Additionally, instructors should emphasize to students that
it is important to sign up for access to the course material
from the beginning. Finally, students should be nudged to
buy the product when the trial period lapses, in order to
avoid having a period of time where they don't have access
to their learning materials.

Ultimately, taking a college course without access to the
learning materials is not a recipe for success. Determining
which interventions can feasibly increase student access to
course materials may be a valuable step towards improving
student outcomes.

The authors would like to thank Stefan Slater for Python code for computing Cliff's Delta in linear time. We would also like to acknowledge Shirin Mojarad and Nick Lewkow for their suggestions for performing analysis.

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LAK '12, pages 267{270, New York, NY, USA, 2012.
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