• 
• 24%
• Unverified Purchases

30 of the 126 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.1 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.

• 
• 37%
• 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 2 groups with a statistically significant greater concentration than what we'd expect to see:

• 16-25 words: 19.8% (Avg. rating: 4.6)
• 26-40 words: 16.7% (Avg. rating: 4.2)

In total, we found that 46 reviews (or 37%) are within an overrepresented word count group. These reviews have rated this product an average of 4.4, while all other reviews 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.

Read more about our Word Count Comparison test.

• 
• 77%
• 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: 47.6% (Avg. rating: 4.2)
• Reviewers with 6-15 Reviews: 29.4% (Avg. rating: 4.0)

In total, we found that 97 reviewers (or 77%) are within an overrepresented participation group. These reviews have rated this product an average of 4.1, while all other reviews have 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.

Read more about our Reviewer Participation test.

• 
• 10%
• Created over 6 days

We counted 126 reviews for this product over the span of 4,323 days, an average of 0.0 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 1 or fewer reviews on any given day.

However, we see the following 6 days exceeding this threshold:

• 2 Reviews on Feb 23, 2013 (Avg. rating: 5.0)
• 2 Reviews on Apr 28, 2013 (Avg. rating: 4.5)
• 2 Reviews on Feb 12, 2016 (Avg. rating: 4.5)
• 2 Reviews on Mar 29, 2016 (Avg. rating: 4.5)
• 2 Reviews on Apr 24, 2015 (Avg. rating: 3.5)
• 2 Reviews on Jan 9, 2017 (Avg. rating: 2.0)

In total, we found that 12 reviews were created on just 6 days. Although any days with a larger number of reviews than expected is suspicious, these reviews do not appear to have a significant impact on the overall rating.

Read more about our Rating Trend test.

One-Hit Wonders

• 
• 13%
• have only posted one review

16 of the 126 reviewers have only reviewed this product. While this is more One-Hit Wonders than we'd expect to see, the discrepancy in ratings between the One-Hit Wonders and reviewers who have posted more than one review isn't significant enough to rule out the possibility of it being due to random chance.

Take-Back Reviewers

• 
• 4%
• have previously deleted reviews

5 of the 126 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.

Single-Day Reviewers

• 
• 19%
• have posted all their reviews on a single day

24 of the 126 reviewers have written multiple reviews but posted all of them on a single day. While this is more Single-Day 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.

• 
• 20%
• Used substantial repetitive phrases

25 of the 126 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.

• 
• 13%
• Substantial overlapping review history

17 of the 126 reviewers have substantial overlapping product review history. 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 Overlapping Review History 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 4.2, while the average ease score for reviewers in this category is 4.4.

Brand Repeaters

• 
• 2%
• Reviewed other products from this brand

2 of the 126 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.

• 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.