Never-Verified Reviewers

• 
• 41%
• have zero verified purchases

154 of the 378 reviewers have never written a verified purchase review. While this is more Never-Verified Reviewers than we'd expect to see, it does not appear to have a significant impact on the overall rating.

Take-Back Reviewers

• 
• 2%
• have previously deleted reviews

8 of the 378 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

6 of the 378 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 5.0 while all other reviewers 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.

Read more about our Suspicious Reviewers test.

• 
• 16%
• Used substantial repetitive phrases

61 of the 378 total reviews for this product use substantial repetitive phrases between them. These reviewers have rated this product an average of 4.3 while reviews without substantial repetitive phrases 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.

Read more about our Phrase Repetition test.

• 2
• Reviews have been deleted

We discovered a total of 2 deleted Reviews for this product, with an average rating of 3.5. 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

• 
• 26%
• Created over 16 days

We counted 378 reviews for this product over the span of 3,812 days, an average of 0.1 reviews per day. If these reviews were created randomly, there would be a 99.9% chance that we would see 2 or fewer reviews on any given day.

However, we see the following 16 days exceeding this threshold:

• 14 Reviews on Jun 16, 2008 (Avg. rating: 3.7)
• 11 Reviews on Jun 13, 2008 (Avg. rating: 2.6)
• 10 Reviews on Jun 14, 2008 (Avg. rating: 4.4)
• 9 Reviews on Jun 15, 2008 (Avg. rating: 3.3)
• 8 Reviews on Jun 18, 2008 (Avg. rating: 4.6)
• 7 Reviews on Jun 12, 2008 (Avg. rating: 4.7)
• 7 Reviews on Jun 17, 2008 (Avg. rating: 3.9)
• 5 Reviews on Jun 21, 2008 (Avg. rating: 2.4)
• 4 Reviews on Jun 22, 2008 (Avg. rating: 4.8)
• 4 Reviews on Jun 20, 2008 (Avg. rating: 3.8)
• 4 Reviews on Jun 9, 2008 (Avg. rating: 3.0)
• 3 Reviews on May 8, 2008 (Avg. rating: 5.0)
• 3 Reviews on Jun 19, 2008 (Avg. rating: 5.0)
• 3 Reviews on Jul 5, 2008 (Avg. rating: 4.0)
• 3 Reviews on Jun 30, 2008 (Avg. rating: 3.3)
• 3 Reviews on Jun 25, 2008 (Avg. rating: 3.0)
Show All

In total, we found that 98 reviews were created on just 16 days. This is an excessively high number of reviews submitted on these high volume days.

Read more about our Rating Trend test.

• 
• 62%
• Unverified Purchases

235 of the 378 total reviews for this product are unverified purchases. While this is a higher percentage of unverified purchases than we'd expect to see, it does not appear to have a significant impact on the overall rating.

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.

• 
• 79%
• From reviewers with an overrepresented participation

We see the following 3 participation groups with a statistically significant greater concentration than what we'd expect to see:

• Reviewers with 1-5 Reviews: 24.6% (Avg. rating: 4.2)
• Reviewers with 6-15 Reviews: 34.9% (Avg. rating: 4.0)
• Reviewers with 16-30 Reviews: 19.1% (Avg. rating: 3.9)

In total, we found that 297 reviewers (or 79%) 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.

• 
• 21%
• 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:

• 101-200 words: 20.6% (Avg. rating: 3.7)

In total, we found that 78 reviews (or 21%) 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.

• 
• 13%
• Substantial overlapping review history

49 of the 378 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 4.1, while the average ease score for reviewers in this category is 4.4.

Brand Repeaters

• 
• 4%
• Reviewed other products from this brand

16 of the 378 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.