The Vitamin D Solution: A 3-Step Strategy to Cure Our Most Common Health Problems
More product info
From Michael F. Holick
Refresh the report to view the most up-to-date data available:
Note: We only analyze "reviews" and ignore one-tap "ratings".
Report Card
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Most Trusted Reviews
TRUST
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Verified Purchaser
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Easy Grader (avg. rating: 4.6)
Least Trusted Reviews
TRUST
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Unverified Purchaser
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Contains repetitive phrases (
show)
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Take-Back Reviewer (3 deleted Reviews; avg. rating: 4.7)
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Overlapping Review History: reviewed 5 of 9 top products
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Easy Grader (avg. rating: 4.9)
Analysis Details
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We discovered a total of 73 deleted Reviews for this product, with an average rating of 4.6. 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.
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6 of the 67 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.
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Take-Back Reviewers
36 of the 67 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.
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- 6%
- Created over 2 days
We counted 67 reviews for this product over the span of 3,344 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 2 days exceeding this threshold:In total, we found that 4 reviews were created on just 2 days. Although any days with a larger number of reviews than expected is suspicious, the discrepancy in ratings from reviews created on these high volume days and reviews created on other days isn't significant enough to rule out the possibility of it being due to random chance.
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4.5 Product's Average Ease Score
4.3 Category's Average Ease Score
Read more about our Reviewer Ease test.
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(4.8/5)
(3.8/5)
(5.0/5)
(5.0/5)
(4.3/5)
(4.5/5)
(5.0/5)
(5.0/5)
(4.8/5)
(5.0/5)
17 of the 67 total reviews for this product use substantial repetitive phrases between them. This is an excessively large percentage which may indicate unnatural reviews.
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- 0%
- Have an overrepresented word count
Read more about our Word Count Comparison test.
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9% also reviewed:
The Magnesium Miracle (Revised and Updated) by Carolyn Dean M.D. N.D
7% also reviewed:
Vitamin K2 and the Calcium Paradox: How a... by Kate Rheaume-Bleue
6% also reviewed:
Could It Be B12?: An Epidemic of Misdiagnoses by Sally M. Pacholok
4% also reviewed:
The Brain That Changes Itself: Stories of... by Norman Doidge
4% also reviewed:
Knockout: Interviews with Doctors Who Are Curing... by Somers, Suzanne
4% also reviewed:
Vitamin C, the Common Cold, and the Flu by Brand: W H Freeman n Co (Sd)
4% also reviewed:
The Devil in Pew Number Seven by Alonzo, Rebecca Nichols/ DeMoss, Robert G. (CON)
4% also reviewed:
Doctor Yourself: Natural Healing That Works by Andrew Saul
4% also reviewed:
Omron HEM-780 Automatic Blood Pressure Monitor... by Omron
16 of the 67 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.
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- 25%
- 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:In total, we found that 17 reviewers (or 25%) 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.
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Brand Repeaters
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- 0%
- Admitted to receiving an incentive
Read more about our Incentivized Reviews test. Check out our study showing that Incentivized Reviewers are much more likely to leave a positive review.