• 193
• Reviews have been deleted

We discovered a total of 193 deleted Reviews for this product, with an average rating of 5. 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

• 
• 81%
• Created over 28 days

We counted 778 reviews for this product over the span of 187 days, an average of 4.2 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 12 or fewer reviews on any given day.

However, we see the following 28 days exceeding this threshold:

• 32 Reviews on Aug 20, 2019 (Avg. rating: 5.0)
• 32 Reviews on Aug 26, 2019 (Avg. rating: 5.0)
• 30 Reviews on Sep 3, 2019 (Avg. rating: 5.0)
• 28 Reviews on Aug 16, 2019 (Avg. rating: 5.0)
• 28 Reviews on Aug 19, 2019 (Avg. rating: 5.0)
• 28 Reviews on Aug 21, 2019 (Avg. rating: 5.0)
• 26 Reviews on Sep 5, 2019 (Avg. rating: 5.0)
• 26 Reviews on Sep 13, 2019 (Avg. rating: 5.0)
• 25 Reviews on Aug 15, 2019 (Avg. rating: 5.0)
• 25 Reviews on Aug 18, 2019 (Avg. rating: 5.0)
• 25 Reviews on Aug 29, 2019 (Avg. rating: 4.8)
• 24 Reviews on Aug 22, 2019 (Avg. rating: 5.0)
• 24 Reviews on Aug 30, 2019 (Avg. rating: 5.0)
• 24 Reviews on Aug 27, 2019 (Avg. rating: 4.8)
• 23 Reviews on Aug 31, 2019 (Avg. rating: 5.0)
• 22 Reviews on Aug 25, 2019 (Avg. rating: 5.0)
• 22 Reviews on Aug 24, 2019 (Avg. rating: 4.9)
• 21 Reviews on Aug 28, 2019 (Avg. rating: 5.0)
• 21 Reviews on Sep 2, 2019 (Avg. rating: 5.0)
• 20 Reviews on Aug 17, 2019 (Avg. rating: 5.0)
• 18 Reviews on Sep 4, 2019 (Avg. rating: 4.8)
• 17 Reviews on Sep 1, 2019 (Avg. rating: 5.0)
• 17 Reviews on Sep 6, 2019 (Avg. rating: 5.0)
• 16 Reviews on Aug 23, 2019 (Avg. rating: 5.0)
• 15 Reviews on Sep 16, 2019 (Avg. rating: 5.0)
• 14 Reviews on Sep 15, 2019 (Avg. rating: 5.0)
• 13 Reviews on Sep 8, 2019 (Avg. rating: 5.0)
• 13 Reviews on Sep 14, 2019 (Avg. rating: 5.0)
Show All

In total, we found that 629 reviews were created on just 28 days. The reviews on these high volume days have rated this product an average of 5.0 while reviews from other days have rated this product an average of 4.8. Based on our statistical modeling, the discrepancy in average rating between these two groups is significant enough to believe that the difference is not due to random chance, and may indicate that there are unnatural reviews.

Read more about our Rating Trend test.

Take-Back Reviewers

• 
• 52%
• have previously deleted reviews

405 of the 778 reviewers have had at least one of their past reviews for another product deleted. This is an excessively large percentage of Take-Back Reviewers which may indicate unnatural reviews.

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 4.9, while the average ease score for reviewers in this category is 4.2. Based on our statistical modeling, the discrepancy in average rating between these two groups is significant enough to believe that the difference is not due to random chance, and may indicate that there are unnatural reviews.

• 
• 70%
• 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 2 groups with a statistically significant greater concentration than what we'd expect to see:

• 66-100 words: 31.0% (Avg. rating: 5.0)
• 101-200 words: 39.0% (Avg. rating: 5.0)

In total, we found that 544 reviews (or 70%) 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.

• 
• 37%
• 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: 37.2% (Avg. rating: 4.9)

In total, we found that 289 reviewers (or 37%) are within an overrepresented participation group. While this is more reviews from overrepresented participation groups than we'd expect to see, these reviews do not appear to have a significant impact on the overall rating.

Read more about our Reviewer Participation test.

• 
• 1%
• Unverified Purchases

10 of the 778 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.

• 
• 32%
• Substantial overlapping review history

252 of the 778 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.

Brand Repeaters

• 
• 16%
• Reviewed other products from this brand

126 of the 778 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.