• 
• 31%
• Unverified Purchases

210 of the 676 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.8 while the verified purchasers have rated this product an average of 4.8. 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.

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.

• 8
• Reviews have been deleted

We discovered a total of 8 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

• 
• 17%
• Created over 12 days

We counted 676 reviews for this product over the span of 4,141 days, an average of 0.2 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 12 days exceeding this threshold:

• 23 Reviews on Dec 10, 2009 (Avg. rating: 4.6)
• 17 Reviews on Dec 9, 2009 (Avg. rating: 5.0)
• 16 Reviews on Dec 11, 2009 (Avg. rating: 2.1)
• 12 Reviews on Dec 15, 2009 (Avg. rating: 5.0)
• 9 Reviews on Dec 12, 2009 (Avg. rating: 2.0)
• 6 Reviews on Dec 23, 2009 (Avg. rating: 5.0)
• 6 Reviews on Dec 14, 2009 (Avg. rating: 4.3)
• 5 Reviews on Dec 24, 2009 (Avg. rating: 5.0)
• 5 Reviews on Dec 16, 2009 (Avg. rating: 4.8)
• 5 Reviews on Dec 28, 2009 (Avg. rating: 4.2)
• 4 Reviews on Dec 20, 2009 (Avg. rating: 5.0)
• 4 Reviews on Jul 21, 2009 (Avg. rating: 4.0)
Show All

In total, we found that 112 reviews were created on just 12 days. This is an excessively high number of reviews submitted on these high volume days.

Read more about our Rating Trend test.

Take-Back Reviewers

• 
• 26%
• have previously deleted reviews

175 of the 676 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.

• 
• 29%
• Used substantial repetitive phrases

196 of the 676 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.

• 
• 33%
• From reviewers with an overrepresented participation

We see the following 1 participation group with a statistically significant greater concentration than what we'd expect to see:

• Reviewers with 1-5 Reviews: 32.8% (Avg. rating: 4.4)

In total, we found that 222 reviewers (or 33%) 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.

• 
• 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.

• 
• 26%
• Substantial overlapping review history

173 of the 676 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 4.3, while the average ease score for reviewers in this category is 4.4.

Brand Repeaters

• 
• 13%
• Reviewed other products from this brand

90 of the 676 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.