• 
• 21%
• Created over 33 days

We counted 1,595 reviews for this product over the span of 3,870 days, an average of 0.4 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 33 days exceeding this threshold:

• 63 Reviews on May 15, 2010 (Avg. rating: 4.9)
• 23 Reviews on Aug 13, 2015 (Avg. rating: 4.6)
• 15 Reviews on May 16, 2010 (Avg. rating: 4.9)
• 15 Reviews on May 17, 2010 (Avg. rating: 4.9)
• 14 Reviews on May 13, 2015 (Avg. rating: 4.8)
• 14 Reviews on Apr 11, 2017 (Avg. rating: 4.8)
• 13 Reviews on Aug 17, 2015 (Avg. rating: 4.4)
• 12 Reviews on Sep 28, 2016 (Avg. rating: 4.8)
• 10 Reviews on Sep 29, 2016 (Avg. rating: 4.6)
• 10 Reviews on Oct 26, 2016 (Avg. rating: 4.5)
• 9 Reviews on Apr 12, 2017 (Avg. rating: 4.9)
• 9 Reviews on Aug 16, 2015 (Avg. rating: 4.8)
• 8 Reviews on Jul 8, 2015 (Avg. rating: 4.5)
• 8 Reviews on Apr 30, 2017 (Avg. rating: 4.1)
• 7 Reviews on Dec 22, 2015 (Avg. rating: 4.7)
• 7 Reviews on Aug 12, 2015 (Avg. rating: 4.6)
• 6 Reviews on Nov 26, 2016 (Avg. rating: 4.8)
• 6 Reviews on Aug 14, 2015 (Avg. rating: 4.5)
• 6 Reviews on Mar 28, 2017 (Avg. rating: 4.5)
• 6 Reviews on Mar 29, 2017 (Avg. rating: 4.3)
• 6 Reviews on Sep 7, 2016 (Avg. rating: 4.0)
• 5 Reviews on Aug 11, 2015 (Avg. rating: 5.0)
• 5 Reviews on Oct 10, 2016 (Avg. rating: 5.0)
• 5 Reviews on Jul 26, 2015 (Avg. rating: 4.8)
• 5 Reviews on Jul 14, 2015 (Avg. rating: 4.8)
• 5 Reviews on Mar 2, 2017 (Avg. rating: 4.8)
• 5 Reviews on Mar 29, 2015 (Avg. rating: 4.8)
• 5 Reviews on Mar 16, 2015 (Avg. rating: 4.8)
• 5 Reviews on May 2, 2017 (Avg. rating: 4.8)
• 5 Reviews on May 29, 2015 (Avg. rating: 4.4)
• 5 Reviews on Apr 18, 2017 (Avg. rating: 4.0)
• 5 Reviews on Oct 17, 2016 (Avg. rating: 3.8)
• 5 Reviews on Oct 31, 2016 (Avg. rating: 2.8)
Show All

In total, we found that 327 reviews were created on just 33 days. The reviews on these high volume days have rated this product an average of 4.7 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.

• 
• 14%
• Unverified Purchases

227 of the 1,595 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 4.5 while the verified purchasers have 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.

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

156 of the 1,595 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 4.3. 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 Overlapping Review History test.

Take-Back Reviewers

• 
• 36%
• have previously deleted reviews

581 of the 1,595 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.

• 
• 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 1,595 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

• 
• 6%
• Reviewed other products from this brand

90 of the 1,595 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

6 of the 1,595 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.