• 
• 51%
• Created over 20 days

We counted 389 reviews for this product over the span of 1,453 days, an average of 0.3 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 3 or fewer reviews on any given day.

However, we see the following 20 days exceeding this threshold:

• 50 Reviews on Jan 11, 2018 (Avg. rating: 4.3)
• 20 Reviews on Jan 12, 2018 (Avg. rating: 4.3)
• 14 Reviews on Jan 8, 2018 (Avg. rating: 4.4)
• 13 Reviews on Jan 10, 2018 (Avg. rating: 4.6)
• 12 Reviews on Jan 14, 2018 (Avg. rating: 4.5)
• 10 Reviews on Jan 13, 2018 (Avg. rating: 4.5)
• 10 Reviews on Jan 9, 2018 (Avg. rating: 3.9)
• 8 Reviews on Jan 5, 2018 (Avg. rating: 4.8)
• 8 Reviews on Jan 7, 2018 (Avg. rating: 4.0)
• 6 Reviews on Nov 11, 2016 (Avg. rating: 4.8)
• 6 Reviews on Jan 15, 2018 (Avg. rating: 4.2)
• 5 Reviews on Nov 12, 2016 (Avg. rating: 4.8)
• 5 Reviews on Nov 13, 2016 (Avg. rating: 4.8)
• 5 Reviews on Jan 6, 2018 (Avg. rating: 4.4)
• 5 Reviews on Mar 10, 2014 (Avg. rating: 3.4)
• 5 Reviews on Mar 11, 2014 (Avg. rating: 3.2)
• 4 Reviews on Jan 17, 2018 (Avg. rating: 5.0)
• 4 Reviews on Jun 10, 2014 (Avg. rating: 4.3)
• 4 Reviews on Nov 19, 2016 (Avg. rating: 4.3)
• 4 Reviews on Nov 16, 2016 (Avg. rating: 4.0)
Show All

In total, we found that 198 reviews were created on just 20 days. The reviews on these high volume days have rated this product an average of 4.3 while reviews from other days have rated this product an average of 4.1. 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.

• 
• 78%
• Unverified Purchases

302 of the 389 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 4.3 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.

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

• 
• 37%
• Substantial overlapping review history

144 of the 389 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 4.4 while the reviewers who have a more unique product review history rated this product an average of 4.1. 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.

On Oct 3, 2016, Amazon prohibited incentivized reviews, however we still test for them since there are still millions in our dataset.

• 
• 16%
• Admitted to receiving an incentive

64 of the 389 total reviews for this product admitted to receiving a free or discounted product in exchange for a review. This is more than we would expect see; the presences of at least one incentivized review indicates that there may be more, since not all reviewers will disclose that they had received an incentive to post a review.

Read more about our Incentivized Reviews test. Check out our study showing that Incentivized Reviewers are much more likely to leave a positive review.

Take-Back Reviewers

• 
• 6%
• have previously deleted reviews

23 of the 389 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.

Read more about our Suspicious Reviewers test.

• 
• 54%
• Used substantial repetitive phrases

211 of the 389 total reviews for this product use substantial repetitive phrases between them. This is an excessively large percentage which may indicate unnatural reviews.

Read more about our Phrase Repetition test.

• 
• 48%
• 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: 15.4% (Avg. rating: 4.3)
• Reviewers with 6-15 Reviews: 32.7% (Avg. rating: 4.2)

In total, we found that 187 reviewers (or 48%) are within an overrepresented participation group. While this is more reviews from overrepresented participation groups than we'd expect to see, these reviews do not appear to have a significant impact on the overall rating.

Read more about our Reviewer Participation test.

• 
• 19%
• Have an overrepresented word count

In the graph above, we can see the distribution of review word counts for this product and the expected distribution for this category. We see the following 1 group with a statistically significant greater concentration than what we'd expect to see:

• 66-100 words: 18.8% (Avg. rating: 4.2)

In total, we found that 73 reviews (or 19%) are within an overrepresented word count 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 Word Count Comparison test.

Brand Repeaters

• 
• 1%
• Reviewed other products from this brand

2 of the 389 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.

• 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.