• 
• 15%
• Unverified Purchases

75 of the 514 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 2.5 while the verified purchasers have rated this product an average of 3.7. 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.

Never-Verified Reviewers

• 
• 3%
• have zero verified purchases

14 of the 514 reviewers have never written a verified purchase review. The Never-Verified Reviewers have rated this product an average of 2.7 while the reviewers who have written at least one verified purchase review rated this product an average of 3.6. 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.

Take-Back Reviewers

• 
• 7%
• have previously deleted reviews

37 of the 514 reviewers have had at least one of their past reviews for another product deleted. While this is more Take-Back Reviewers than we'd expect to see, it does not appear to have a significant impact on the overall rating.

Read more about our Suspicious Reviewers test.

• 
• 3%
• Used substantial repetitive phrases

17 of the 514 total reviews for this product use substantial repetitive phrases between them. These reviewers have rated this product an average of 4.7 while reviews without substantial repetitive phrases rated this product an average of 3.5. 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.

Read more about our Phrase Repetition test.

• 
• 17%
• Substantial overlapping review history

88 of the 514 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 4.0 while the reviewers who have a more unique product review history rated this product an average of 3.4. 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.

• 
• 38%
• Created over 21 days

We counted 514 reviews for this product over the span of 636 days, an average of 0.8 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 5 or fewer reviews on any given day.

However, we see the following 21 days exceeding this threshold:

• 18 Reviews on Dec 16, 2016 (Avg. rating: 3.8)
• 18 Reviews on Dec 25, 2016 (Avg. rating: 3.8)
• 15 Reviews on Dec 17, 2016 (Avg. rating: 3.6)
• 13 Reviews on Dec 26, 2016 (Avg. rating: 3.6)
• 13 Reviews on Dec 19, 2016 (Avg. rating: 3.4)
• 11 Reviews on Dec 9, 2016 (Avg. rating: 4.1)
• 10 Reviews on Dec 12, 2016 (Avg. rating: 4.4)
• 10 Reviews on Jan 2, 2017 (Avg. rating: 4.4)
• 9 Reviews on Dec 7, 2016 (Avg. rating: 2.8)
• 8 Reviews on Dec 20, 2016 (Avg. rating: 3.9)
• 8 Reviews on Dec 18, 2016 (Avg. rating: 3.5)
• 8 Reviews on Dec 28, 2016 (Avg. rating: 3.4)
• 7 Reviews on Dec 24, 2016 (Avg. rating: 3.7)
• 7 Reviews on Dec 30, 2016 (Avg. rating: 3.1)
• 6 Reviews on Dec 2, 2016 (Avg. rating: 5.0)
• 6 Reviews on Dec 22, 2016 (Avg. rating: 4.5)
• 6 Reviews on Dec 15, 2016 (Avg. rating: 4.2)
• 6 Reviews on Nov 23, 2015 (Avg. rating: 3.8)
• 6 Reviews on Dec 14, 2016 (Avg. rating: 3.3)
• 6 Reviews on Dec 13, 2016 (Avg. rating: 2.5)
• 6 Reviews on Nov 9, 2015 (Avg. rating: 2.3)
Show All

In total, we found that 197 reviews were created on just 21 days. This is an excessively high number of reviews submitted on these high volume days.

Read more about our Rating Trend test.

• 
• 74%
• 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: 26.5% (Avg. rating: 3.6)
• Reviewers with 6-15 Reviews: 47.7% (Avg. rating: 3.6)

In total, we found that 381 reviewers (or 74%) 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.

• 
• 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.

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 4.3.

Brand Repeaters

We didn't detect a substantial amount of Brand Repeaters.

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.