• 
• 28%
• Created over 7 days

We counted 260 reviews for this product over the span of 115 days, an average of 2.3 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 8 or fewer reviews on any given day.

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

• 15 Reviews on Jul 25, 2019 (Avg. rating: 5.0)
• 12 Reviews on Jul 24, 2019 (Avg. rating: 5.0)
• 10 Reviews on Jul 23, 2019 (Avg. rating: 5.0)
• 10 Reviews on Jul 29, 2019 (Avg. rating: 5.0)
• 9 Reviews on Jul 13, 2019 (Avg. rating: 5.0)
• 9 Reviews on Jul 22, 2019 (Avg. rating: 5.0)
• 9 Reviews on Aug 2, 2019 (Avg. rating: 5.0)
Show All

In total, we found that 74 reviews were created on just 7 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 4.7. 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.

• 
• 1%
• Unverified Purchases

3 of the 260 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.3 while the verified purchasers 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.

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

• 
• 5%
• have only posted one review

12 of the 260 reviewers have only reviewed this product. The One-Hit Wonders have rated this product an average of 3.8 while the reviewers who have posted more than one review 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.

Never-Verified Reviewers

• 
• 1%
• have zero verified purchases

2 of the 260 reviewers have never written a verified purchase review. The Never-Verified Reviewers have rated this product an average of 2.5 while the reviewers who have written at least one verified purchase review 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 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 4.7, 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.

• 
• 65%
• 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:

• 41-65 words: 38.1% (Avg. rating: 4.8)
• 66-100 words: 27.3% (Avg. rating: 4.9)

In total, we found that 170 reviews (or 65%) are within an overrepresented word count group. These reviews have rated this product an average of 4.8, while all other reviews have rated this product an average of 4.6. 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 Word Count Comparison test.

• 
• 40%
• Substantial overlapping review history

104 of the 260 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 5.0 while the reviewers who have a more unique product review history rated this product an average of 4.6. 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 Overlapping Review History test.

• 
• 44%
• 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: 44.2% (Avg. rating: 4.9)

In total, we found that 115 reviewers (or 44%) are within an overrepresented participation group. These reviews have rated this product an average of 4.9, while all other reviews have rated this product an average of 4.6. 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 Reviewer Participation 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.