• 58
• Reviews have been deleted

We discovered a total of 58 deleted Reviews for this product, with an average rating of 4.9. 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

• 
• 5%
• Created over 3 days

We counted 335 reviews for this product over the span of 525 days, an average of 0.6 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 4 or fewer reviews on any given day.

However, we see the following 3 days exceeding this threshold:

• 8 Reviews on May 25, 2019 (Avg. rating: 4.9)
• 5 Reviews on Dec 5, 2018 (Avg. rating: 4.8)
• 5 Reviews on Dec 19, 2018 (Avg. rating: 4.6)

In total, we found that 18 reviews were created on just 3 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 4.2. 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 Rating Trend test.

Brand Loyalists

• 
• 6%
• Reviewed mostly products from this brand

19 of the 335 reviewers have reviewed multiple products but half or more of their reviews are for this brand. This is an excessively large percentage of Brand Loyalists which may indicate unnatural reviews.

Brand Monogamists

• 
• 4%
• Reviewed only products from this brand

14 of the 335 reviewers have reviewed multiple products, but only for this brand. This is an excessively large percentage of Brand Monogamists which may indicate unnatural reviews.

Read more about our Brand Repeats test.

One-Hit Wonders

• 
• 11%
• have only posted one review

37 of the 335 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.

Single-Day Reviewers

• 
• 4%
• have posted all their reviews on a single day

13 of the 335 reviewers have written multiple reviews but posted all of them on a single day. The Single-Day reviewers have rated this product an average of 4.9 while all other reviewers 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.

• 
• 50%
• 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:

• 66-100 words: 26.9% (Avg. rating: 4.6)
• 101-200 words: 23.3% (Avg. rating: 4.5)

In total, we found that 168 reviews (or 50%) are within an overrepresented word count group. These reviews have rated this product an average of 4.6, while all other reviews have rated this product an average of 4.0. 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.

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.

• 
• 51%
• 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: 50.8% (Avg. rating: 4.1)

In total, we found that 170 reviewers (or 51%) 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.

• 
• 7%
• Unverified Purchases

25 of the 335 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.

• 
• 10%
• Substantial overlapping review history

35 of the 335 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.

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.