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Natrol Biotin Maximum Strength 100 Tablets
More product info From Natrol

Brigade Warning!:
Our algorithm has detected a large amount of suspicious negative reviews. Learn more about Review Brigades.
Amazon Reviews for  Natrol Biotin Maximum Strength 100 Tablets
Rating:
254 Ratings
229 Reviews
("Ratings" vs. "Reviews")
30% of potentially unnatural reviews removed (why?)
Adjusted:
View/Edit Adjustment
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Report Info:
Last Updated: Mar 11, 2017
Refresh Report
Note: While Amazon.ca claims 254 Ratings, we counted 229 Reviews available on their site.
Note: We only analyze "reviews" and ignore one-tap "ratings".

Report Card

Warn Overall Grade
FAIL Rating Trend
FAIL Unverified Purchases
FAIL Suspicious Reviewers
FAIL Word Count Comparison
FAIL Overlapping Review History
PASS Phrase Repetition
PASS Reviewer Participation
PASS Reviewer Ease
PASS Brand Repeats
PASS Incentivized Reviews
PASS Deleted Reviews

Most Trusted Reviews

Have been taking it for a month but don't really ... [Go to full review]
Dec 29, 2016      
100% TRUST
  • Verified Purchaser
  • Critical Reviewer (avg. rating: 4.1)


Least Trusted Reviews

It doesn't work... wasting.. [Go to full review]
Nov 16, 2016      
0% TRUST
  • Unverified Purchaser
  • Created on a high volume day
  • Overrepresented word count (4 words)
  • One-Hit Wonder
  • Never-Verified Reviewer
  • Critical Reviewer (avg. rating: 1.0)


Analysis Details

Fail Rating Trend

  • 6%
  • Created over 3 days

We counted 229 reviews for this product over the span of 1,440 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 3 days exceeding this threshold:In total, we found that 13 reviews were created on just 3 days. The reviews on these high volume days have rated this product an average of 1.6 while reviews from other days have rated this product an average of 4.1. 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.

from reviews created on high volume days

from reviews created on normal volume days


1.6
4.1


Read more about our Rating Trend test.

Fail Unverified Purchases

23 of the 229 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 1.9 while the verified purchasers have rated this product an average of 4.2. 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.

from unverified purchasers

from verified purchases


1.9
4.2


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.

Fail Suspicious Reviewers

One-Hit Wonders


45 of the 229 reviewers have only reviewed this product. While this is more One-Hit Wonders than we'd expect to see, it does not appear to have a significant impact on the overall rating.

from one-hit wonders

from reviewers with more than one review


3.6
4.1


Never-Verified Reviewers


17 of the 229 reviewers have never written a verified purchase review. The Never-Verified Reviewers have rated this product an average of 1.4 while the reviewers who have written at least one verified purchase review rated this product an average of 4.2. 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.

from never-verified reviewers

from reviewers with at least one verified purchase review


1.4
4.2


Take-Back Reviewers


10 of the 229 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.

from take-back reviewers

from reviewers without previously deleted reviews


3.6
4.0


Read more about our Suspicious Reviewers test.

Fail Word Count Comparison

  • 33%
  • 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 75 reviews (or 33%) are within an overrepresented word count group. These reviews have rated this product an average of 4.4, while all other reviews have rated this product an average of 3.8. 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.

from reviews with an overrepresented word count

from reviews with a properly represented word count


4.4
3.8


Read more about our Word Count Comparison test.

Fail Overlapping Review History
Reviewers of this product have ALSO reviewed the following products:



32 of the 229 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 3.2 while the reviewers who have a more unique product review history rated this product an average of 4.1. 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.

from reviewers with substantial overlapping history

from reviewers without a substantial overlapping history


3.2
4.1


Read more about our Overlapping Review History test.

Pass Phrase Repetition
Reviews that contain one of these phrases are NOT necessarily devalued; read more about how this test works here.

Common Phrases in Titles:
3 reviews


10 of the 229 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.

from reviews with substantial repetitive phrases

from reviews without substantial repetitive phrases


3.5
4.0


Read more about our Phrase Repetition test.

Pass Reviewer Participation

  • 0%
  • From reviewers with an overrepresented participation
We didn't find any participation groups that had a statistically significant greater concentration than what we'd expect to see in this category.
Read more about our Reviewer Participation test.

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, while the average ease score for reviewers in this category is 4.3.

4.0 Product's Average Ease Score

4.3 Category's Average Ease Score


4.0
4.3


Read more about our Reviewer Ease test.


Pass Brand Repeats

Brand Repeaters


9 of the 229 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.

from Brand Repeaters

from Non-Repeaters


4.8
3.9


Read more about our Brand Repeats test.

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.

Pass Deleted Reviews
  • 0
  • Reviews have been deleted
We have not discovered any deleted reviews for this product.

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.