• 63
• Reviews have been deleted

We discovered a total of 63 deleted Reviews for this product, with an average rating of 5. 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

• 
• 39%
• Created over 3 days

We counted 23 reviews for this product over the span of 276 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 3 days exceeding this threshold:

• 3 Reviews on Jan 23, 2019 (Avg. rating: 5.0)
• 3 Reviews on Mar 12, 2019 (Avg. rating: 5.0)
• 3 Reviews on Mar 25, 2019 (Avg. rating: 5.0)

In total, we found that 9 reviews were created on just 3 days. This is an excessively high number of reviews submitted on these high volume days.

Read more about our Rating Trend test.

Brand Repeaters

• 
• 39%
• Reviewed other products from this brand

9 of the 23 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.

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 4.7, 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.

• 
• 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 1 group with a statistically significant greater concentration than what we'd expect to see:

• 26-40 words: 65.2% (Avg. rating: 4.7)

In total, we found that 15 reviews (or 65%) 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.

• 
• 61%
• Substantial overlapping review history

14 of the 23 reviewers have substantial overlapping product review history. While this is more than we'd expect to see, the discrepancy in ratings between these reviewers and reviewers who have a more unique product review history isn't significant enough to rule out the possibility of it being due to random chance.

Read more about our Overlapping Review History test.

• 
• 65%
• 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: 65.2% (Avg. rating: 5.0)

In total, we found that 15 reviewers (or 65%) are within an overrepresented participation group. This is an excessively high number of reviewers in overrepresented participation groups.

Read more about our Reviewer Participation test.

• 
• 4%
• Unverified Purchases

1 of the 23 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.

One-Hit Wonders

We didn't detect a substantial amount of One Hit Wonders.

Never-Verified Reviewers

• 
• 4%
• have zero verified purchases

1 of the 23 reviewers have never written a verified purchase review. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Take-Back Reviewers

• 
• 9%
• have previously deleted reviews

2 of the 23 reviewers have had at least one of their past reviews for another product deleted. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

Single-Day Reviewers

We didn't detect a substantial amount of Single-Day Reviewers.

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.