We found fewer average reviews per
day than Pagano and Maalej20 possibly
due to any of several factors. The first
is we collected reviews from stable top
apps that had been released for at least
one year, whereas Pagano and Maalej20
may have collected new apps and not
focused on top apps. The second was
that our estimates for the frequently reviewed apps were conservative; we did
not count more than 500 reviews in a
day. For instance, Pagano and Maalej reported that Facebook received 4,275 reviews in a day, with such large numbers
increasing the overall reported average
number of received reviews on a daily
basis. We separated the apps into two
groups: 100 most-reviewed apps and
all other apps. Figure 1b reports there
was a large gap in the total number of
reviews among the 100 most-reviewed
apps. The total number of reviews of the
100 most-reviewed apps ranged from
43,000 to 6,000 in the two-month study
period. The reviews themselves were
short, much shorter (approximately
40%) than the reviews in the Apple App
Store. We also observed a notable skew
in the length of reviews in both stores.
Influence of app category and downloads on number of reviews. In the
Google Play Store
Finding 3. The number of downloads
and releases correlated with the number of received reviews, whereas an
app’s category did not play a major role
during the study period. On the other
hand, Pagano and Maalej20 and Hoon
11 both reported a relation between
an app’s category and the number of received reviews; and
Implication. The relationship between number of received reviews and
an app’s category should be explored
further, especially in light of the discrepancy between the two app stores.
Here, we investigate the effect of an
app’s number of downloads, number
of releases, and app category on the
number of received reviews. We built a
regression model with an app’s number
of received reviews as the dependent
variable. Due to the notable skew in the
number of reviews, we log-transformed
the number of reviews before building
the linear-regression model.
Figure 2 plots the total number of reviews using the built-regression model.
We included three plots, each keeping
the median values of the other factors
interested in stable, mature apps that
had not been released within the past
few months to avoid the expected burst
of reviews following an app’s initial re-
20 We focused on free-to-download
apps, since recent work showed that
free apps receive five times as many re-
views as paid apps.
20 Moreover, over 90%
of downloaded apps were, at the time,
of the free-to-download variety, accord-
ing to Gartner. Such apps use other rev-
enue models (such as freemium, in-app
purchases, and ads). The developers of
such apps are thus concerned about the
effect of reviews on their revenue.
Here, we present our findings, as in Table 2, concerning the reviews from the
Google Play store while comparing our
results with prior studies.
Number of received reviews. On
the number of received reviews in the
Google Play Store
Finding 1. Most apps (88% of those
of the 10,713 we studied) received few
reviews during our studied time period.
The average and median number of
reviews were fewer than Pagano’s and
Maalej20 and greater than Hoon et al.;
Finding 2. The number of user reviews were skewed; similar findings
were reported by Pagano and Maalej;
Implication. Most top apps might
not benefit much from automated approaches to analyzing reviews that leverage sophisticated techniques (such
as topic modeling) given the small number of received user reviews and their
We plotted the number of reviews per
day, as well as total number of received
reviews, using a beanplot combining
a boxplot with a kernel-density-esti-mation function. Figure 1a reports the
median number of reviews per day was
0. We found 20, or 0.19%, of the 10,713
studied apps received 500 or more reviews; as mentioned earlier, 500 would
be a conservative estimate, whereas 88%
of the apps in our 10,713-app dataset received fewer than 20 reviews per day. Additionally, the median total number of
reviews was 0 during the study period.
We also calculated the number of words
in each of the received reviews, with median number of words per review at 46.
Table 2. Datasets of prior work mining reviews of mobile apps.
Paper App Store Apps Reviews
Iacob and Harrison12 Google Play Store 161 3,279
Galvis and Carreno7 Google Play Store 2 710
Fu et al.
6 Google Play Store 171,493 13,286,706
Chen et al.
5 Google Play Store 4 169,097
Pagano and Maalej21 Apple App Store 1, 100 1,126,453
Hoon et al.
11 Apple App Store 17,000 8,700,000
Figure 1. Beanplots showing number of reviews per day and in total.
All other 100 most reviewed