Is it Live or is it Internet? Experimental Estimates of the

advertisement
Is it Live or is it Internet?
Experimental Estimates of the
Effects of Online Instruction on
Student Learning
David Figlio, Northwestern U
Mark Rush, U Florida
Lu Yin, American Institutes for Research
Background
• Two major trends affecting higher education
– Declining state and local appropriations  more
fiscal challenges, increasing demands for
“efficiency” (new NRC panel)
– Rapid improvements in technology
• As a consequence, millions of students are
now taking classes online
What do online classes look like?
• Two major types:
– Innovative, highly interactive classes aimed at
exploiting special nature of the internet and modern
technology
– Traditional lectures presented in an online format
• While door #1 is the type of class advocated by
learning scientists (NB: I’m working with
colleagues to develop this type of class in high
school science), door #2 is what most universities
are doing.
What is the causal question of
interest?
• Do students learn more in a traditional lecture
when it is broadcast on the internet than when
it is presented in a standard lecture hall?
• In principle, the results could be positive or
negative:
– Pro: increased flexibility; no need to rely on
others’ notes; ability to annotate/rewatch lectures
– Con: increased barriers to student-faculty
interaction; reduced ability to ask just in time
questions; incentives to defer work
What is the causal question of
interest? (part 2)
• Are there heterogeneous effects of internetbased traditional lectures on students?
• Why interesting?
– Some groups may face additional communication
barriers (e.g., language minority students)
– Some groups may have lower self-regulation skills
(e.g., college-aged men; relatively lowerachievers)
What is the evidence to date?
• Almost nothing
• Mainly small-scale case studies; unsurprisingly,
almost all studies are based on type 1 of internetbased class rather than type 2 of internet-based
class
• Somewhat larger studies have poor treatmentcontrol contrast
• Considerable need for experimental evidence on
both types of internet class, but especially the
broadcast-traditional-lecture type  this study
What is the ideal experiment?
• Treatment and control students should be taught in tandem
– Same instructor, same exams, same lectures, same supplementary
material, same readings
• Pure randomization to live vs. internet treatment
– No opt-out from experiment
• No opportunities for contamination of treatment and control
– Live students cannot view internet lectures; internet students cannot
attend live lectures
• Ample opportunities for detecting heterogeneous effects and
improving external validity
– Dozens of experiments in different courses at different institutions,
with within-course randomization
– Cluster-randomized design; clustering on subgroups to ensure
sufficient sample size to detect subgroup-specific effects
Fidelity to ideal experiment
• Treatment and control students should be taught in tandem
– Same instructor, same exams, same lectures, same supplementary
material, same readings
• Pure randomization to live vs. internet treatment
– No opt-out from experiment (instead: randomization of volunteers)
• No opportunities for contamination of treatment and control
– Live students cannot view internet lectures; internet students cannot
attend live lectures (live students may potentially watch with friends)
• Ample opportunities for detecting heterogeneous effects and
improving external validity (nope: just one class, no group cluster)
– Dozens of experiments in different courses at different institutions,
with within-course randomization
– Cluster-randomized design; clustering on subgroups to ensure
sufficient sample size to detect subgroup-specific effects
Threats to
internal and external validity
• (1) Volunteers, rather than pure
randomization
– How representative are volunteers of the potential
study population at the institution? [external
validity]  Table 1
– Knowledge that this is an experiment might lead
to differential attrition of live vs. internet [internal
validity]  Table 2 contrasts; bounding exercise in
Table 3
Threats to
internal and external validity
• (2) Fidelity of randomization and lack of treatment
contamination
– Do people drop from experiment post-randomization?
[internal validity]  as 15 students assigned to “live”
dropped from the experiment, Table 3 compares results
treating defectors as “live” versus dropping from study
– Do “live” students view internet version and do “internet”
students attend live lecture? [internal validity]
• Door guards checked IDs so we know that no “internet” students
attended live lectures
• Live students did not have online access, but could have accessed
via friends’ log-ins  Figure 1 shows that “live” students attended
substantially more lectures than “live+internet” non-volunteers
Threats to
internal and external validity
• Intro economics might be special
• The university in question might be unusual
• The particular instructor may translate
well/poorly to the internet platform
Lots of hand-wringing
And also a call for more experiments in other
subjects and settings and with a design aimed
at detecting heterogeneous treatment effects
Threats to
internal and external validity
• (1) Volunteers, rather than pure randomization
– How representative are volunteers of the potential
study population at the institution? [external validity]
 some differences; volunteers had higher GPAs and
lower SAT scores and mom was less likely to be a
college grad.
– Knowledge that this is an experiment might lead to
differential attrition of live vs. internet [internal
validity]  no evidence of differential attrition: 6 live,
10 online attriters, and no differences between them.
Bounding exercise (giving attriters scores of 0 or 100
on missed exam) shows tight bounds when
considering attrition.
Threats to
internal and external validity
• (2) Fidelity of randomization and lack of treatment
contamination
– Do people drop from experiment post-randomization? [internal
validity]  no differences in results when we treat defecting
volunteers as “live” versus when we drop them from the study
– Do “live” students view internet version and do “internet”
students attend live lecture? [internal validity]  can’t know for
certain about live students viewing lectures online, but it looks
like live students definitely attend more live lectures than those
with the choice. Note that there is a “professional” private notetaking and tutoring service that is very popular and available to
all students regardless of live/online. Other studies at the
institution on cramming indicate that many internet coursetakers don’t view all (or most, or sometimes any) of the lectures
either
Threats to
internal and external validity
• Intro economics might be special
• The university in question might be unusual
• The particular instructor may translate
well/poorly to the internet platform
This is important, and there’s nothing we can
do about this except to call for more
experiments
Results
• Small insignificant positive estimated effects of
live-only vs. internet-only instruction; statistically
significant (mostly due to larger coefficients
rather than smaller standard errors) when
conditioning on covariates
• Positive estimated effects are largest for Hispanic
students (sig) and Asian students (not sig); male
students (not sig) and students with relatively low
SAT scores (not sig)  larger sample sizes and
cluster randomization might have helped detect
differences here
Conclusions
• There might be efficiencies to exploit with
internet-based traditional lectures, but there
is no free lunch
• The results of this experiment should be
interpreted as a first piece of evidence;
responsible universities should be slow to
implement this policy change despite the
momentum and push for this. We need many
more – including larger -- experiments!
Download