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 5, 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.

• 
• 71%
• Created over 5 days

We counted 17 reviews for this product over the span of 518 days, an average of 0.0 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 1 or fewer reviews on any given day.

However, we see the following 5 days exceeding this threshold:

• 4 Reviews on Sep 4, 2018 (Avg. rating: 5.0)
• 2 Reviews on Sep 18, 2018 (Avg. rating: 5.0)
• 2 Reviews on Dec 26, 2019 (Avg. rating: 5.0)
• 2 Reviews on Dec 30, 2019 (Avg. rating: 5.0)
• 2 Reviews on Dec 31, 2019 (Avg. rating: 5.0)

In total, we found that 12 reviews were created on just 5 days. This is an excessively high number of reviews submitted on these high volume days.

Read more about our Rating Trend test.

Never-Verified Reviewers

• 
• 35%
• have zero verified purchases

6 of the 17 reviewers have never written a verified purchase review. While this is more Never-Verified Reviewers 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.

• 
• 41%
• Unverified Purchases

7 of the 17 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.

• 
• 0%
• Have an overrepresented word count

We didn't find any review word count groups that had a statistically significant greater concentration than what we'd expect to see in this category.
Read more about our Word Count Comparison test.

• 
• 24%
• Substantial overlapping review history

4 of the 17 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%
• From reviewers with an overrepresented participation

We didn't find any participation groups that had a statistically significant greater concentration than what we'd expect to see in this category.
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.