• 
• 7%
• Unverified Purchases

140 of the 1,976 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.2 while the verified purchasers 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.

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

• 
• 8%
• have only posted one review

160 of the 1,976 reviewers have only reviewed this product. The One-Hit Wonders have rated this product an average of 3.3 while the reviewers who have posted more than one review 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.

Never-Verified Reviewers

• 
• 1%
• have zero verified purchases

14 of the 1,976 reviewers have never written a verified purchase review. The Never-Verified Reviewers have rated this product an average of 2.0 while the reviewers who have written at least one verified purchase review 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.

Take-Back Reviewers

• 
• 43%
• have previously deleted reviews

846 of the 1,976 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 4.2 while the reviewers who don't have any deleted reviews in their history have rated this product an average of 3.8. 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.

Single-Day Reviewers

• 
• 3%
• have posted all their reviews on a single day

65 of the 1,976 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 4.4 while all other reviewers 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 Suspicious Reviewers test.

• 
• 12%
• Substantial overlapping review history

246 of the 1,976 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 4.3 while the reviewers who have a more unique product review history rated this product an average of 3.9. 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.

• 62
• Reviews have been deleted

We discovered a total of 62 deleted Reviews for this product, with an average rating of 4.4. 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

• 
• 7%
• Created over 27 days

We counted 1,976 reviews for this product over the span of 3,136 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 27 days exceeding this threshold:

• 8 Reviews on Dec 6, 2015 (Avg. rating: 4.9)
• 7 Reviews on Feb 16, 2016 (Avg. rating: 4.0)
• 6 Reviews on Oct 20, 2015 (Avg. rating: 4.7)
• 6 Reviews on May 18, 2015 (Avg. rating: 4.2)
• 6 Reviews on Jun 12, 2015 (Avg. rating: 4.2)
• 6 Reviews on Oct 2, 2016 (Avg. rating: 4.0)
• 6 Reviews on Aug 6, 2015 (Avg. rating: 3.8)
• 5 Reviews on Aug 19, 2014 (Avg. rating: 5.0)
• 5 Reviews on May 30, 2015 (Avg. rating: 5.0)
• 5 Reviews on Oct 19, 2015 (Avg. rating: 4.8)
• 5 Reviews on Mar 9, 2015 (Avg. rating: 4.6)
• 5 Reviews on Jul 22, 2015 (Avg. rating: 4.6)
• 5 Reviews on Nov 4, 2015 (Avg. rating: 4.6)
• 5 Reviews on Jan 25, 2016 (Avg. rating: 4.4)
• 5 Reviews on Nov 23, 2014 (Avg. rating: 4.2)
• 5 Reviews on Mar 19, 2015 (Avg. rating: 4.2)
• 5 Reviews on Feb 26, 2015 (Avg. rating: 4.0)
• 5 Reviews on Mar 8, 2015 (Avg. rating: 4.0)
• 5 Reviews on Sep 20, 2015 (Avg. rating: 4.0)
• 5 Reviews on Oct 9, 2014 (Avg. rating: 3.8)
• 5 Reviews on Feb 15, 2015 (Avg. rating: 3.8)
• 5 Reviews on Feb 21, 2015 (Avg. rating: 3.8)
• 5 Reviews on Jul 9, 2015 (Avg. rating: 3.8)
• 5 Reviews on Oct 8, 2015 (Avg. rating: 3.8)
• 5 Reviews on Dec 29, 2015 (Avg. rating: 3.8)
• 5 Reviews on Feb 25, 2016 (Avg. rating: 3.4)
• 5 Reviews on Feb 8, 2016 (Avg. rating: 2.4)
Show All

In total, we found that 145 reviews were created on just 27 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.

• 
• 0%
• Used substantial repetitive phrases

0 of the 1,976 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.

• 
• 26%
• 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: 25.8% (Avg. rating: 3.9)

In total, we found that 509 reviewers (or 26%) are within an overrepresented participation 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 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 4.1, while the average ease score for reviewers in this category is 4.1.

Brand Repeaters

• 
• 3%
• Reviewed other products from this brand

54 of the 1,976 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.