• 
• 16%
• Unverified Purchases

336 of the 2,111 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.8 while the verified purchasers have rated this product an average of 4.5. 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

• 
• 5%
• have only posted one review

106 of the 2,111 reviewers have only reviewed this product. The One-Hit Wonders have rated this product an average of 3.7 while the reviewers who have posted more than one review have rated this product an average of 4.5. 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

• 
• 15%
• have previously deleted reviews

326 of the 2,111 reviewers have had at least one of their past reviews for another product deleted. This is an excessively large percentage of Take-Back Reviewers which may indicate unnatural reviews.

Single-Day Reviewers

• 
• 5%
• have posted all their reviews on a single day

102 of the 2,111 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 4.6 while all other reviewers 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.

Read more about our Suspicious Reviewers test.

• 
• 9%
• Substantial overlapping review history

188 of the 2,111 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 4.6 while the reviewers who have a more unique product review history 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.

Read more about our Overlapping Review History test.

• 
• 5%
• Created over 20 days

We counted 2,111 reviews for this product over the span of 3,626 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 20 days exceeding this threshold:

• 9 Reviews on Sep 11, 2012 (Avg. rating: 4.3)
• 7 Reviews on Aug 31, 2012 (Avg. rating: 4.9)
• 6 Reviews on Sep 19, 2012 (Avg. rating: 4.8)
• 6 Reviews on Jan 14, 2016 (Avg. rating: 4.8)
• 6 Reviews on Feb 18, 2016 (Avg. rating: 4.8)
• 6 Reviews on Sep 10, 2012 (Avg. rating: 4.3)
• 6 Reviews on Dec 3, 2015 (Avg. rating: 3.8)
• 6 Reviews on Oct 29, 2015 (Avg. rating: 3.7)
• 5 Reviews on Feb 29, 2016 (Avg. rating: 5.0)
• 5 Reviews on May 6, 2016 (Avg. rating: 5.0)
• 5 Reviews on Sep 17, 2012 (Avg. rating: 4.8)
• 5 Reviews on Dec 9, 2014 (Avg. rating: 4.8)
• 5 Reviews on Dec 1, 2015 (Avg. rating: 4.8)
• 5 Reviews on Mar 22, 2016 (Avg. rating: 4.8)
• 5 Reviews on Apr 28, 2016 (Avg. rating: 4.8)
• 5 Reviews on Sep 7, 2012 (Avg. rating: 4.6)
• 5 Reviews on Jan 20, 2015 (Avg. rating: 4.6)
• 5 Reviews on May 25, 2015 (Avg. rating: 4.2)
• 5 Reviews on Mar 26, 2016 (Avg. rating: 4.2)
• 5 Reviews on Aug 22, 2016 (Avg. rating: 4.2)
Show All

In total, we found that 112 reviews were created on just 20 days. Although any days with a larger number of reviews than expected is suspicious, the discrepancy in ratings from reviews created on these high volume days and reviews created on other days isn't significant enough to rule out the possibility of it being due to random chance.

Read more about our Rating Trend 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.

• 
• 3%
• Used substantial repetitive phrases

56 of the 2,111 total reviews for this product use substantial repetitive phrases between them. 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 Phrase Repetition 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.

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 4.3.

Brand Repeaters

• 
• 7%
• Reviewed other products from this brand

146 of the 2,111 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

2 of the 2,111 total reviews for this product admitted to receiving a free or discounted product in exchange for a review. 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 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.