• 
• 7%
• Created over 8 days

We counted 544 reviews for this product over the span of 1,612 days, an average of 0.3 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 3 or fewer reviews on any given day.

However, we see the following 8 days exceeding this threshold:

• 6 Reviews on Aug 16, 2015 (Avg. rating: 5.0)
• 6 Reviews on Dec 25, 2016 (Avg. rating: 4.5)
• 5 Reviews on Sep 25, 2015 (Avg. rating: 5.0)
• 5 Reviews on Mar 16, 2016 (Avg. rating: 5.0)
• 4 Reviews on Oct 20, 2015 (Avg. rating: 5.0)
• 4 Reviews on Sep 27, 2015 (Avg. rating: 4.8)
• 4 Reviews on Sep 30, 2015 (Avg. rating: 4.8)
• 4 Reviews on Oct 14, 2015 (Avg. rating: 4.8)
Show All

In total, we found that 38 reviews were created on just 8 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 4.6. 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 Rating Trend test.

Never-Verified Reviewers

• 
• 2%
• have zero verified purchases

12 of the 544 reviewers have never written a verified purchase review. The Never-Verified Reviewers have rated this product an average of 3.8 while the reviewers who have written at least one verified purchase review 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 Suspicious Reviewers test.

Brand Repeaters

• 
• 29%
• Reviewed other products from this brand

156 of the 544 reviewers have reviewed other products for this brand. While this is more Brand Repeaters than we'd expect to see, the discrepancy in ratings between the Brand Repeaters and non-repeaters isn't significant enough to rule out the possibility of it being due to random chance.

Brand Loyalists

• 
• 4%
• Reviewed mostly products from this brand

20 of the 544 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, it does not appear to have a significant impact on the overall rating.

Read more about our Brand Repeats 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.

• 
• 100%
• 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: 99.6% (Avg. rating: 4.6)

In total, we found that 542 reviews (or 100%) 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.

• 
• 43%
• 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: 43.4% (Avg. rating: 4.6)

In total, we found that 236 reviewers (or 43%) 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.

• 
• 8%
• Unverified Purchases

42 of the 544 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.

• 
• 11%
• Substantial overlapping review history

62 of the 544 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.

• 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.