• 
• 34%
• Created over 16 days

We counted 182 reviews for this product over the span of 2,457 days, an average of 0.1 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 2 or fewer reviews on any given day.

However, we see the following 16 days exceeding this threshold:

• 5 Reviews on Feb 2, 2019 (Avg. rating: 5.0)
• 5 Reviews on May 11, 2019 (Avg. rating: 5.0)
• 5 Reviews on Jun 5, 2019 (Avg. rating: 5.0)
• 5 Reviews on Jun 27, 2019 (Avg. rating: 5.0)
• 5 Reviews on Jul 10, 2019 (Avg. rating: 4.2)
• 4 Reviews on Jan 7, 2019 (Avg. rating: 5.0)
• 4 Reviews on May 9, 2019 (Avg. rating: 5.0)
• 4 Reviews on Aug 5, 2019 (Avg. rating: 4.5)
• 3 Reviews on May 24, 2019 (Avg. rating: 5.0)
• 3 Reviews on Jun 28, 2019 (Avg. rating: 5.0)
• 3 Reviews on Jul 9, 2019 (Avg. rating: 5.0)
• 3 Reviews on Jul 25, 2019 (Avg. rating: 5.0)
• 3 Reviews on Aug 31, 2019 (Avg. rating: 5.0)
• 3 Reviews on May 14, 2019 (Avg. rating: 4.7)
• 3 Reviews on Jan 26, 2019 (Avg. rating: 4.3)
• 3 Reviews on May 7, 2019 (Avg. rating: 4.3)
Show All

In total, we found that 61 reviews were created on just 16 days. The reviews on these high volume days have rated this product an average of 4.8 while reviews from other days have rated this product an average of 4.1. 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.

• 
• 62%
• 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: 24.2% (Avg. rating: 4.5)
• 66-100 words: 37.9% (Avg. rating: 4.5)

In total, we found that 113 reviews (or 62%) are within an overrepresented word count group. These reviews have rated this product an average of 4.5, while all other reviews have rated this product an average of 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.

Read more about our Word Count Comparison test.

• 
• 11%
• Substantial overlapping review history

20 of the 182 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 4.8 while the reviewers who have a more unique product review history rated this product an average of 4.3. 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.

• 
• 80%
• 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 1-5 Reviews: 79.7% (Avg. rating: 4.5)

In total, we found that 145 reviewers (or 80%) are within an overrepresented participation group. These reviews have rated this product an average of 4.5, while all other reviews have rated this product an average of 3.9. 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.

One-Hit Wonders

• 
• 10%
• have only posted one review

19 of the 182 reviewers have only reviewed this product. While this is more One-Hit Wonders 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 4.3, 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.

• 
• 5%
• Unverified Purchases

10 of the 182 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.