• 
• 16%
• Created over 13 days

We counted 658 reviews for this product over the span of 511 days, an average of 1.3 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:

• 11 Reviews on Dec 11, 2019 (Avg. rating: 4.8)
• 10 Reviews on Dec 14, 2019 (Avg. rating: 4.9)
• 9 Reviews on Jan 6, 2020 (Avg. rating: 4.6)
• 9 Reviews on Jan 13, 2020 (Avg. rating: 4.0)
• 9 Reviews on Jan 19, 2020 (Avg. rating: 4.0)
• 8 Reviews on Dec 9, 2019 (Avg. rating: 4.6)
• 8 Reviews on Dec 15, 2019 (Avg. rating: 4.6)
• 8 Reviews on Dec 12, 2019 (Avg. rating: 4.4)
• 7 Reviews on Dec 10, 2019 (Avg. rating: 4.9)
• 7 Reviews on Mar 1, 2020 (Avg. rating: 4.9)
• 7 Reviews on Dec 26, 2019 (Avg. rating: 4.6)
• 7 Reviews on Jan 11, 2020 (Avg. rating: 4.6)
• 7 Reviews on Jan 4, 2020 (Avg. rating: 4.4)
Show All

In total, we found that 107 reviews were created on just 13 days. The reviews on these high volume days have rated this product an average of 4.6 while reviews from other days have 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 Rating Trend test.

One-Hit Wonders

• 
• 29%
• have only posted one review

190 of the 658 reviewers have only reviewed this product. The One-Hit Wonders have rated this product an average of 4.5 while the reviewers who have posted more than one review have 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 Suspicious Reviewers test.

• 
• 68%
• 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: 67.9% (Avg. rating: 4.4)

In total, we found that 447 reviewers (or 68%) are within an overrepresented participation group. These reviews have rated this product an average of 4.4, while all other reviews 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 Reviewer Participation test.

• 24
• Reviews have been deleted

We discovered a total of 24 deleted Reviews for this product, with an average rating of 4.3. 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

Brand Loyalists

• 
• 3%
• Reviewed mostly products from this brand

18 of the 658 reviewers have reviewed multiple products but half or more of their reviews are for this brand. While this is more Brand Loyalists than we'd expect to see, the discrepancy in ratings between the Brand Loyalists and non-loyalists isn't significant enough to rule out the possibility of it being due to random chance.

Read more about our Brand Repeats test.

• 
• 97%
• 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: 97.0% (Avg. rating: 4.3)

In total, we found that 638 reviews (or 97%) 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.

• 
• 2%
• Unverified Purchases

16 of the 658 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.

• 
• 2%
• Substantial overlapping review history

16 of the 658 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 4.3, 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.

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.