• 
• 10%
• Created over 29 days

We counted 1,824 reviews for this product over the span of 3,097 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 29 days exceeding this threshold:

• 14 Reviews on Sep 7, 2011 (Avg. rating: 4.3)
• 11 Reviews on Sep 9, 2011 (Avg. rating: 4.4)
• 11 Reviews on Sep 12, 2011 (Avg. rating: 4.2)
• 8 Reviews on Sep 10, 2011 (Avg. rating: 4.9)
• 8 Reviews on Jan 12, 2014 (Avg. rating: 4.3)
• 8 Reviews on Sep 8, 2011 (Avg. rating: 4.0)
• 7 Reviews on Sep 11, 2011 (Avg. rating: 4.9)
• 6 Reviews on Feb 10, 2013 (Avg. rating: 4.8)
• 6 Reviews on Sep 14, 2011 (Avg. rating: 4.7)
• 6 Reviews on Sep 26, 2011 (Avg. rating: 4.5)
• 6 Reviews on Mar 21, 2012 (Avg. rating: 4.3)
• 5 Reviews on Sep 6, 2011 (Avg. rating: 5.0)
• 5 Reviews on Jan 11, 2013 (Avg. rating: 5.0)
• 5 Reviews on Jan 20, 2013 (Avg. rating: 5.0)
• 5 Reviews on Apr 19, 2013 (Avg. rating: 5.0)
• 5 Reviews on Feb 17, 2012 (Avg. rating: 4.8)
• 5 Reviews on Mar 5, 2012 (Avg. rating: 4.8)
• 5 Reviews on Dec 28, 2012 (Avg. rating: 4.8)
• 5 Reviews on Jan 30, 2013 (Avg. rating: 4.8)
• 5 Reviews on Sep 20, 2011 (Avg. rating: 4.6)
• 5 Reviews on Nov 28, 2011 (Avg. rating: 4.6)
• 5 Reviews on Jan 24, 2012 (Avg. rating: 4.6)
• 5 Reviews on Feb 21, 2013 (Avg. rating: 4.6)
• 5 Reviews on Sep 23, 2011 (Avg. rating: 4.4)
• 5 Reviews on Jan 5, 2012 (Avg. rating: 4.4)
• 5 Reviews on Aug 7, 2013 (Avg. rating: 4.4)
• 5 Reviews on Jan 1, 2013 (Avg. rating: 4.2)
• 5 Reviews on Jul 7, 2013 (Avg. rating: 4.0)
• 5 Reviews on Oct 23, 2014 (Avg. rating: 3.6)
Show All

In total, we found that 181 reviews were created on just 29 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 4.3. 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 Rating Trend test.

Take-Back Reviewers

• 
• 36%
• have previously deleted reviews

664 of the 1,824 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, the discrepancy in ratings between the Take-Back Reviewers and reviewers who don't have any deleted reviews in their history isn't significant enough to rule out the possibility of it being due to random chance.

Single-Day Reviewers

• 
• 2%
• have posted all their reviews on a single day

43 of the 1,824 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 4.3. 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 Suspicious Reviewers test.

• 
• 4%
• Used substantial repetitive phrases

82 of the 1,824 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 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.

• 
• 13%
• Substantial overlapping review history

238 of the 1,824 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.

• 70
• Reviews have been deleted

We discovered a total of 70 deleted Reviews for this product, with an average rating of 4.3. 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

Brand Repeaters

• 
• 29%
• Reviewed other products from this brand

522 of the 1,824 reviewers have reviewed other products for this brand. While this is more Brand Repeaters than we'd expect to see, the discrepancy in ratings between the Brand Repeaters and non-repeaters isn't significant enough to rule out the possibility of it being due to random chance.

Read more about our Brand Repeats test.

• 
• 59%
• 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: 27.4% (Avg. rating: 4.3)
• Reviewers with 6-15 Reviews: 31.6% (Avg. rating: 4.4)

In total, we found that 1076 reviewers (or 59%) 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.

• 
• 17%
• Unverified Purchases

304 of the 1,824 total reviews for this product are unverified purchases. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.

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.

• 
• 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 4.3, while the average ease score for reviewers in this category is 4.3.

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.