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Delta Sleep System
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From Dr. Jeffrey Thompson
This report was last updated 12/30/2020.
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Report Info:
Note: While Amazon.com claims 233 Ratings, we counted 204 Reviews available on their site.
Note: We only analyze "reviews" and ignore one-tap "ratings".
Note: We only analyze "reviews" and ignore one-tap "ratings".
Top products in CDs & Vinyl with authentic reviews:
Report Card
Warn Overall Grade
FAIL Deleted Reviews
FAIL Suspicious Reviewers
WARN Rating Trend
WARN Phrase Repetition
WARN Reviewer Participation
PASS Unverified Purchases
PASS Word Count Comparison
PASS Overlapping Review History
PASS Reviewer Ease
PASS Brand Repeats
PASS Incentivized Reviews
Most Trusted Reviews
I have used this for massage therapy in many sessions.Only ... [Go to full review]
Feb 20, 2019
100%
TRUST
TRUST
- Verified Purchaser
- Easy Grader (avg. rating: 4.6)
Least Trusted Reviews
The Delta Sync Sleep System works very well by calming ... [Go to full review]
Jun 26, 2001
0%
TRUST
TRUST
- Unverified Purchaser
- Created on a high volume day
- Contains repetitive phrases (show)
- Never-Verified Reviewer
- Single-Day Reviewer (posted all reviews on Jun 26, 2001)
- Brand Monogamist (2 of 2 reviews for this brand; avg rating: 5.0)
- Overrepresented Participation (posted 2 Reviews)
- Easy Grader (avg. rating: 5.0)
Analysis Details
Fail Deleted Reviews
We discovered a total of 11 deleted Reviews for this product, with an average rating of 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:
- 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.
- We have no information on reviews that were never published in the first place.
- 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.
Fail Suspicious Reviewers
Never-Verified Reviewers
26 of the 204 reviewers have never written a verified purchase review. The Never-Verified Reviewers have rated this product an average of 4.3 while the reviewers who have written at least one verified purchase review rated this product an average of 3.7. 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.
Take-Back Reviewers
97 of the 204 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.
Warn Rating Trend
-
- 5%
- Created over 5 days
We counted 204 reviews for this product over the span of 7,419 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 5 days exceeding this threshold:In total, we found that 11 reviews were created on just 5 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.
Warn Phrase Repetition
Reviews that contain one of these phrases are NOT necessarily devalued; read more about how this test works here.
Common Phrases in Reviews:
Show MoreShow Less
i got up several times in a night because i would go insane if i stayed in bed wide awake any longer
2 reviews
(5.0/5)
(5.0/5)
2 reviews
(5.0/5)
(5.0/5)
13 reviews
(3.5/5)
(3.5/5)
5 reviews
(3.4/5)
(3.4/5)
2 reviews
(5.0/5)
(5.0/5)
5 reviews
(4.2/5)
(4.2/5)
2 reviews
(5.0/5)
(5.0/5)
2 reviews
(5.0/5)
(5.0/5)
Common Phrases in Titles:
2 reviews
(4.0/5)
(4.0/5)
5 reviews
(4.0/5)
(4.0/5)
3 reviews
(2.0/5)
(2.0/5)
39 of the 204 total reviews for this product use substantial repetitive phrases between them. This is an excessively large percentage which may indicate unnatural reviews.
Warn Reviewer Participation
-
- 64%
- 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:In total, we found that 130 reviewers (or 64%) are within an overrepresented participation group. This is an excessively high number of reviewers in overrepresented participation groups.
Pass Unverified Purchases
71 of the 204 total reviews for this product are unverified purchases. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.
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.
Pass Word Count Comparison
-
- 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:In total, we found that 42 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.
Pass Overlapping Review History
Reviewers of this product have ALSO reviewed the following products:
3% also reviewed:
Theta Meditation System by Dr. Jeffrey Thompson
2% also reviewed:
American Gods: The Tenth Anniversary Edition: A... by Neil Gaiman
2% also reviewed:
The No-Grain Diet: Conquer Carbohydrate Addiction... by Mercola, Joseph/ Levy, Alison Rose
2% also reviewed:
Delta Sleep System 2.0 by Relaxation
2% also reviewed:
Awakened Mind System by Dr. Jeffrey Thompson
2% also reviewed:
Outward Hound Hide A Rainbow Plush Dog Toy Puzzle by Outward Hound
2% also reviewed:
Hanes Women's Cool Comfort Cotton Brief... by Hanes
Does not include products
from the same brand
from the same brand
31 of the 204 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.
Pass Reviewer Ease
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.
4.2 Product's Average Ease Score
4.4 Category's Average Ease Score
Read more about our Reviewer Ease test.
Pass Brand Repeats
Brand Monogamists
1 of the 204 reviewers have reviewed multiple products, but only for this brand. This is within an acceptable range and it does not appear to be significantly affecting the overall rating for this product.
Pass Incentivized Reviews
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.
Read more about our Incentivized Reviews test. Check out our study showing that Incentivized Reviewers are much more likely to leave a positive review.