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Shimano Tz31 21 Speed the 7 Speed of Mountain Bike Direct Mount Rear Derailleur
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From Shimano
This report was last updated 5/12/2018.
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Report Info:
Last Updated: May 12, 2018
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Note: We only analyze "reviews" and ignore one-tap "ratings".
Report Card
Warn Overall Grade
FAIL Rating Trend
FAIL Word Count Comparison
WARN Deleted Reviews
WARN Suspicious Reviewers
WARN Reviewer Participation
PASS Unverified Purchases
PASS Phrase Repetition
PASS Overlapping Review History
PASS Reviewer Ease
PASS Brand Repeats
PASS Incentivized Reviews
Most Trusted Reviews
This is the Tz31A, not the product listed, unable to ... [Go to full review]
Aug 3, 2017
100%
TRUST
TRUST
- Verified Purchaser
- Critical Reviewer (avg. rating: 4.3)
Least Trusted Reviews
Junk No Good [Go to full review]
Sep 15, 2017
0%
TRUST
TRUST
- Verified Purchaser
- Created on a high volume day
- Overrepresented word count (3 words)
- Take-Back Reviewer (1 deleted Review; avg. rating: 5.0)
- Overrepresented Participation (posted 11 Reviews)
- Critical Reviewer (avg. rating: 2.7)
Analysis Details
Fail Rating Trend
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- 6%
- Created over 2 days
We counted 113 reviews for this product over the span of 807 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 2 days exceeding this threshold:In total, we found that 7 reviews were created on just 2 days. The reviews on these high volume days have rated this product an average of 2.7 while reviews from other days have 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.
Fail Word Count Comparison
-
- 63%
- 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 2 groups with a statistically significant greater concentration than what we'd expect to see:In total, we found that 71 reviews (or 63%) are within an overrepresented word count group. These reviews have rated this product an average of 4.2, while all other reviews have rated this product an average of 3.5. 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.
Warn Deleted Reviews
We discovered a total of 1 deleted Review for this product, with an average rating of 4. 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.
Warn Suspicious Reviewers
Take-Back Reviewers
3 of the 113 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 Reviewer Participation
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- 71%
- From reviewers with an overrepresented participation
We see the following 2 participation groups with a statistically significant greater concentration than what we'd expect to see:In total, we found that 80 reviewers (or 71%) are within an overrepresented participation group. This is an excessively high number of reviewers in overrepresented participation groups.
Pass Unverified Purchases
4 of the 113 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 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:
2 reviews
4 of the 113 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.
Pass Overlapping Review History
Reviewers of this product have ALSO reviewed the following products:
12% also reviewed:
Oumers Universal Bike Chain Tool with Chain Hook,... by Oumers
3% also reviewed:
Amazon.com Gift Card Balance Reload by Amazon
2% also reviewed:
Amazon Store Card by Synchrony Bank
2% also reviewed:
JOTO Universal Waterproof Pouch Cellphone Dry Bag... by JOTO
2% also reviewed:
FOXNOVO Adjustable Kickstand Kick Stand Mount for... by Foxnovo
2% also reviewed:
Mongoora Bike & Motorcycle Phone and GPS... by Mongoora
25 of the 113 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 4.1, while the average ease score for reviewers in this category is 4.3.
4.1 Product's Average Ease Score
4.3 Category's Average Ease Score
Read more about our Reviewer Ease test.
Pass Brand Repeats
Brand Repeaters
1 of the 113 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.
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.