• 10
• Reviews have been deleted

We discovered a total of 10 deleted Reviews for this product, with an average rating of 3.3. Even though deleted reviews don't affect the average rating, the fact that action was taken to delete reviews raises some red flags about the integrity of the reviews for the product as whole.

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.

Show distribution of deleted reviews

• 
• 98%
• 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: 98.3% (Avg. rating: 4.3)

In total, we found that 4,279 reviews (or 98%) 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.

• 
• 42%
• From reviewers with an overrepresented participation

We see the following 1 participation group with a statistically significant greater concentration than what we'd expect to see:

• Reviewers with 6-15 Reviews: 41.7% (Avg. rating: 4.3)

In total, we found that 1813 reviewers (or 42%) are within an overrepresented participation group. While this is more reviews from overrepresented participation groups than we'd expect to see, the discrepancy in ratings between reviewers in an overrepresented participation groups and all other reviewers isn’t significant enough to rule out the possibility of it being due to random chance.

Read more about our Reviewer Participation test.

• 
• 2%
• Created over 13 days

We counted 4,353 reviews for this product over the span of 3,519 days, an average of 1.2 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 6 or fewer reviews on any given day.

However, we see the following 13 days exceeding this threshold:

• 8 Reviews on Feb 19, 2017 (Avg. rating: 4.8)
• 8 Reviews on Jul 2, 2018 (Avg. rating: 4.8)
• 8 Reviews on Dec 17, 2017 (Avg. rating: 4.4)
• 8 Reviews on Jan 9, 2018 (Avg. rating: 3.5)
• 7 Reviews on Feb 6, 2018 (Avg. rating: 4.6)
• 7 Reviews on Jan 6, 2019 (Avg. rating: 4.6)
• 7 Reviews on Apr 22, 2019 (Avg. rating: 4.4)
• 7 Reviews on Nov 11, 2017 (Avg. rating: 4.3)
• 7 Reviews on Jul 1, 2018 (Avg. rating: 4.3)
• 7 Reviews on Jan 24, 2016 (Avg. rating: 4.1)
• 7 Reviews on Mar 1, 2016 (Avg. rating: 4.1)
• 7 Reviews on Feb 1, 2018 (Avg. rating: 4.0)
• 7 Reviews on Feb 22, 2015 (Avg. rating: 2.9)
Show All

In total, we found that 95 reviews were created on just 13 days. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Read more about our Rating Trend test.

• 
• 4%
• Unverified Purchases

168 of the 4,353 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.

One-Hit Wonders

• 
• 4%
• have only posted one review

178 of the 4,353 reviewers have only reviewed this product. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Never-Verified Reviewers

• 
• 1%
• have zero verified purchases

57 of the 4,353 reviewers have never written a verified purchase review. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Take-Back Reviewers

• 
• 16%
• have previously deleted reviews

715 of the 4,353 reviewers have had at least one of their past reviews for another product deleted. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Single-Day Reviewers

• 
• 2%
• have posted all their reviews on a single day

78 of the 4,353 reviewers have written multiple reviews but posted all of them on a single day. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Read more about our Suspicious Reviewers test.

• 
• 12%
• Substantial overlapping review history

531 of the 4,353 reviewers have substantial overlapping product review history. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Read more about our Overlapping Review History 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 4.2, while the average ease score for reviewers in this category is 4.2.

Brand Repeaters

• 
• 10%
• Reviewed other products from this brand

438 of the 4,353 reviewers have reviewed other products for this brand. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Read more about our Brand Repeats 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.