• 
• 30%
• Created over 21 days

We counted 440 reviews for this product over the span of 2,428 days, an average of 0.2 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 21 days exceeding this threshold:

• 15 Reviews on Nov 29, 2010 (Avg. rating: 4.9)
• 10 Reviews on Dec 7, 2010 (Avg. rating: 4.7)
• 10 Reviews on Dec 8, 2010 (Avg. rating: 4.7)
• 8 Reviews on Nov 27, 2010 (Avg. rating: 4.9)
• 8 Reviews on Oct 26, 2010 (Avg. rating: 4.1)
• 7 Reviews on Dec 3, 2010 (Avg. rating: 4.4)
• 7 Reviews on Oct 29, 2010 (Avg. rating: 4.3)
• 7 Reviews on Dec 1, 2010 (Avg. rating: 4.3)
• 6 Reviews on Dec 11, 2010 (Avg. rating: 5.0)
• 6 Reviews on Jan 2, 2011 (Avg. rating: 4.8)
• 5 Reviews on Nov 26, 2010 (Avg. rating: 5.0)
• 5 Reviews on Dec 27, 2010 (Avg. rating: 5.0)
• 5 Reviews on Dec 6, 2010 (Avg. rating: 4.2)
• 5 Reviews on Dec 5, 2010 (Avg. rating: 3.6)
• 5 Reviews on Dec 28, 2010 (Avg. rating: 3.2)
• 4 Reviews on Nov 23, 2010 (Avg. rating: 5.0)
• 4 Reviews on Jan 5, 2011 (Avg. rating: 5.0)
• 4 Reviews on Nov 28, 2010 (Avg. rating: 4.5)
• 4 Reviews on Dec 22, 2010 (Avg. rating: 4.3)
• 4 Reviews on Oct 28, 2010 (Avg. rating: 3.0)
• 4 Reviews on Nov 16, 2010 (Avg. rating: 3.0)
Show All

In total, we found that 133 reviews were created on just 21 days. The reviews on these high volume days have rated this product an average of 4.5 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.

• 
• 31%
• Unverified Purchases

138 of the 440 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.6 while the verified purchasers 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.

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

• 
• 13%
• have only posted one review

56 of the 440 reviewers have only reviewed this product. While this is more One-Hit Wonders than we'd expect to see, the discrepancy in ratings between the One-Hit Wonders and reviewers who have posted more than one review isn't significant enough to rule out the possibility of it being due to random chance.

Never-Verified Reviewers

• 
• 9%
• have zero verified purchases

40 of the 440 reviewers have never written a verified purchase review. The Never-Verified Reviewers have rated this product an average of 3.5 while the reviewers who have written at least one verified purchase review rated this product an average of 4.4. 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.

Take-Back Reviewers

• 
• 10%
• have previously deleted reviews

44 of the 440 reviewers have had at least one of their past reviews for another product deleted. The Take-Back Reviewers have rated this product an average of 4.8 while the reviewers who don't have any deleted reviews in their history 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 Suspicious Reviewers 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. 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.

• 
• 4%
• Used substantial repetitive phrases

16 of the 440 total reviews for this product use substantial repetitive phrases between them. These reviewers have rated this product an average of 4.9 while reviews without substantial repetitive phrases 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 Phrase Repetition test.

• 
• 62%
• From reviewers with an overrepresented participation

We see the following 2 participation groups with a statistically significant greater concentration than what we'd expect to see:

• Reviewers with 1-5 Reviews: 36.4% (Avg. rating: 4.4)
• Reviewers with 6-15 Reviews: 25.2% (Avg. rating: 4.0)

In total, we found that 271 reviewers (or 62%) 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.

• 
• 20%
• 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: 20.2% (Avg. rating: 4.2)

In total, we found that 89 reviews (or 20%) are within an overrepresented word count group. 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 Word Count Comparison test.

• 
• 30%
• Substantial overlapping review history

130 of the 440 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.

Brand Repeaters

• 
• 12%
• Reviewed other products from this brand

53 of the 440 reviewers have reviewed other products for this brand. 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 Brand Repeats test.

On Oct 3, 2016, Amazon prohibited incentivized reviews, however we still test for them since there are still millions in our dataset.

• 
• 0%
• Admitted to receiving an incentive

We didn't detect any reviews that used language indicating they were incentivized.
Read more about our Incentivized Reviews test. Check out our study showing that Incentivized Reviewers are much more likely to leave a positive review.

• 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.