• 
• 42%
• Unverified Purchases

316 of the 748 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.4 while the verified purchasers have rated this product an average of 4.4. 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.

Take-Back Reviewers

• 
• 20%
• have previously deleted reviews

151 of the 748 reviewers have had at least one of their past reviews for another product deleted. This is an excessively large percentage of Take-Back Reviewers which may indicate unnatural reviews.

Read more about our Suspicious Reviewers test.

• 3
• Reviews have been deleted

We discovered a total of 3 deleted Reviews for this product, with an average rating of 2.7. 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

• 
• 11%
• Created over 17 days

We counted 748 reviews for this product over the span of 3,328 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 17 days exceeding this threshold:

• 9 Reviews on Nov 25, 2008 (Avg. rating: 3.4)
• 8 Reviews on Jan 7, 2009 (Avg. rating: 3.6)
• 6 Reviews on Nov 27, 2008 (Avg. rating: 4.0)
• 6 Reviews on Jul 5, 2008 (Avg. rating: 3.3)
• 6 Reviews on Nov 26, 2008 (Avg. rating: 3.3)
• 6 Reviews on Dec 5, 2008 (Avg. rating: 3.2)
• 5 Reviews on Jul 2, 2008 (Avg. rating: 3.8)
• 4 Reviews on Jan 6, 2009 (Avg. rating: 4.5)
• 4 Reviews on Dec 6, 2008 (Avg. rating: 4.3)
• 4 Reviews on Jan 9, 2009 (Avg. rating: 4.3)
• 4 Reviews on Jul 6, 2008 (Avg. rating: 3.5)
• 4 Reviews on Nov 28, 2008 (Avg. rating: 3.3)
• 4 Reviews on Nov 30, 2008 (Avg. rating: 3.3)
• 4 Reviews on Jan 15, 2009 (Avg. rating: 3.3)
• 4 Reviews on Jul 11, 2008 (Avg. rating: 3.0)
• 4 Reviews on Jul 10, 2008 (Avg. rating: 2.8)
• 4 Reviews on Dec 27, 2008 (Avg. rating: 2.8)
Show All

In total, we found that 86 reviews were created on just 17 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.

Brand Repeaters

• 
• 39%
• Reviewed other products from this brand

295 of the 748 reviewers have reviewed other products for this brand. While this is more Brand Repeaters than we'd expect to see, it does not appear to have a significant impact on the overall rating.

Read more about our Brand Repeats 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.

• 
• 5%
• Used substantial repetitive phrases

36 of the 748 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.

• 
• 30%
• Substantial overlapping review history

224 of the 748 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.

• 
• 22%
• 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: 21.5% (Avg. rating: 4.0)

In total, we found that 161 reviewers (or 22%) are within an overrepresented participation 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 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 4.1, 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.