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Calculus
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From Larson, Ron/ Edwards, Bruce
This report was last updated 2/20/2018.
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Last Updated: Feb 20, 2018
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Note: We only analyze "reviews" and ignore one-tap "ratings".
Report Card
Warn Overall Grade
FAIL Unverified Purchases
FAIL Overlapping Review History
WARN Deleted Reviews
WARN Suspicious Reviewers
WARN Reviewer Participation
PASS Rating Trend
PASS Word Count Comparison
PASS Phrase Repetition
PASS Reviewer Ease
PASS Brand Repeats
PASS Incentivized Reviews
Most Trusted Reviews
This was packaged well and arrived in great condition. [Go to full review]
Apr 7, 2017
100%
TRUST
TRUST
- Verified Purchaser
- Overrepresented word count (9 words)
- Take-Back Reviewer (5 deleted Reviews; avg. rating: 5.0)
- Easy Grader (avg. rating: 4.8)
Least Trusted Reviews
where are the answers for Appendix C. Precalus Review Exercises? [Go to full review]
Aug 28, 2016
0%
TRUST
TRUST
- Unverified Purchaser
- Overrepresented word count (10 words)
- One-Hit Wonder
- Never-Verified Reviewer
- Overrepresented Participation (posted 1 Review)
- Critical Reviewer (avg. rating: 3.0)
Analysis Details
Fail Unverified Purchases
18 of the 127 total reviews for this product are unverified purchases. The unverified purchasers have rated this product an average of 3.6 while the verified purchasers have rated this product an average of 4.4. 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.
Fail Overlapping Review History
Reviewers of this product have ALSO reviewed the following products:
4% also reviewed:
AmazonBasics High-Speed HDMI Cable - 6.5 Feet (2... by AmazonBasics
2% also reviewed:
Physics: Principles with Applications Volume 1... by Douglas Giancoli
2% also reviewed:
Campbell Biology (10th Edition) - Softcover by Jane B. Reece
2% also reviewed:
Assassin's Creed III by Ubisoft
2% also reviewed:
Texas Instruments TI-30X IIS 2-Line Scientific... by Texas Instruments
Does not include products
from the same brand
from the same brand
19 of the 127 reviewers have substantial overlapping product review history. These reviewers have rated this product an average of 3.6 while the reviewers who have a more unique product review history rated this product an average of 4.4. 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 2 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.
Warn Suspicious Reviewers
One-Hit Wonders
31 of the 127 reviewers have only reviewed this product. While this is more One-Hit Wonders than we'd expect to see, the discrepancy in ratings between the One-Hit Wonders and reviewers who have posted more than one review isn't significant enough to rule out the possibility of it being due to random chance.
Take-Back Reviewers
10 of the 127 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
-
- 57%
- 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 72 reviewers (or 57%) are within an overrepresented participation group. This is an excessively high number of reviewers in overrepresented participation groups.
Pass Rating Trend
-
- 0%
- Created on high-volume days
We counted 127 reviews for this product over the span of 1,747 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. We didn't find any days exceeding this threshold.
Read more about our Rating Trend test.
Read more about our Rating Trend test.
Pass Word Count Comparison
-
- 25%
- 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 32 reviews (or 25%) 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 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 127 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 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 4.3.
4.2 Product's Average Ease Score
4.3 Category's Average Ease Score
Read more about our Reviewer Ease test.
Pass Brand Repeats
Brand Repeaters
5 of the 127 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.