• 
• 52%
• Created over 7 days

We counted 111 reviews for this product over the span of 161 days, an average of 0.7 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 5 or fewer reviews on any given day.

However, we see the following 7 days exceeding this threshold:

• 10 Reviews on Sep 21, 2019 (Avg. rating: 4.3)
• 9 Reviews on Sep 22, 2019 (Avg. rating: 4.8)
• 9 Reviews on Sep 17, 2019 (Avg. rating: 4.6)
• 9 Reviews on Sep 15, 2019 (Avg. rating: 4.4)
• 8 Reviews on Sep 16, 2019 (Avg. rating: 4.4)
• 7 Reviews on Oct 6, 2019 (Avg. rating: 3.9)
• 6 Reviews on Sep 29, 2019 (Avg. rating: 4.7)
Show All

In total, we found that 58 reviews were created on just 7 days. This is an excessively high number of reviews submitted on these high volume days.

Read more about our Rating Trend test.

Take-Back Reviewers

• 
• 26%
• have previously deleted reviews

29 of the 111 reviewers have had at least one of their past reviews for another product deleted. While this is more Take-Back Reviewers than we'd expect to see, it does not appear to have a significant impact on the overall rating.

Read more about our Suspicious Reviewers test.

The ease score is the average rating for all reviews that a given reviewer submits. The average ease score for reviewers of this product is 4.4, while the average ease score for reviewers in this category is 4.2. While this discrepancy is rather large, it is not quite large enough to rule out the possibility of it being due random chance.

• 
• 91%
• Have an overrepresented word count

In the graph above, we can see the distribution of review word counts for this product and the expected distribution for this category. We see the following 1 group with a statistically significant greater concentration than what we'd expect to see:

• 0-5 words: 91.0% (Avg. rating: 4.4)

In total, we found that 101 reviews (or 91%) are within an overrepresented word count group. This is an excessively high number of reviews in overrepresented word count groups.

Read more about our Word Count Comparison test.

• 
• 77%
• Substantial overlapping review history

86 of the 111 reviewers have substantial overlapping product review history. This is an excessively large percentage which may indicate unnatural reviews.

Read more about our Overlapping Review History test.

• 
• 88%
• From reviewers with an overrepresented participation

We see the following 3 participation groups with a statistically significant greater concentration than what we'd expect to see:

• Reviewers with 31-50 Reviews: 24.3% (Avg. rating: 3.9)
• Reviewers with 51-100 Reviews: 46.9% (Avg. rating: 4.6)
• Reviewers with 101-200 Reviews: 17.1% (Avg. rating: 4.4)

In total, we found that 98 reviewers (or 88%) are within an overrepresented participation group. This is an excessively high number of reviewers in overrepresented participation groups.

Read more about our Reviewer Participation test.

• 
• 0%
• Unverified Purchases

0 of the 111 total reviews for this product are unverified purchases. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.
Unverified purchases may be the result of Kindle Unlimited readers, buyers who didn't pay full price, or reviewers who did not purchase the product at Amazon. Read more about our Unverified Purchases test.

Brand Repeaters

We didn't detect a substantial amount of Brand Repeaters.

• 0
• Reviews have been deleted

We have not discovered any deleted reviews for this product.

There are a few limitations to keep in mind regarding the Deleted Reviews test:

1. We don't have a magic ability to collect every single deleted review; we can only identify reviews as deleted if we collect them on one date and then notice they are no longer visible on a subsequent date.
2. We have no information on reviews that were never published in the first place.
3. We also don't know why these reviews were removed. It could be action from the platform, personal decision by the review author, part of an entire account closure, even some data error on our part, etc.

Read more about our Deleted Reviews test.

We have not yet completed optimization for this test for Hanzi or Kanji.

We have not yet completed optimization for this test for Hanzi or Kanji.