1. Chemistry & STEAM Fundamentals II
Precision & Accuracy

2. William Tell: his Son & the Arrow
14th Century Swiss Legend & Subject of Rossini’s 1829 Opera
William Tell (in the four languages of Switzerland: German: Wilhelm Tell; French: Guillaume Tell; Italian: Guglielmo Tell; Romansh: Guglielm Tell) is a folk hero of Switzerland. His legend is recorded in a late 15th-century Swiss illustrated chronicle. It is set in the time of the original foundation of the Old Swiss Confederacy in the early 14th century. According to the legend, Tell—an expert marksman with the crossbow—
he could redeem his son’s life by shooting an apple off the head of his son, Walter, in a single attempt. Tell split the apple with a bolt from his crossbow.
assassinated Gessler, a tyrannical reeve of Habsburg Austria positioned in Altdorf, Uri.

3. Precision QUESTION: Rank the images from best to worst precision.
A) a > b > c B) b > c > a C) c > a > b D) c > b > a

4. Accuracy QUESTION: Rank the images from best to worst accuracy.
A) a > b > c B) b > c > a C) c > a > b D) c > b > a

5. QUESTION
Two Chem 106 students are each drinking a can of cranberry juice after class. The printed label indicates that the respective volume of both containers is 375 milliliters. Hanna remarks that the Federal Trade Commision (FTC) requires bottlers to be very precise. Nikko correctly responded:
If precision were the only requirement, bottlers could claim any volume as long as it was always very nearly the same volume.
Since precision is a requirement, bottlers have to get exactly mL in every can.
Bottlers must have a precise average of all of the containers in a case of soft drinks equal to 375 mL.
If there were a difference of no more than +/- 1 mL between containers, the bottlers can sell their beverage.

6. Precision & Accuracy (The Following Measured Data is for Volume in mL)

7. QUESTION
The melting point of pure benzoic acid is 122°C. Data obtained by four students in a laboratory experiment are shown below. Which student’s data are the most precise but not the most accurate?
A) Student A (115+/-2.5oC) B) Student B (119+/-0.8oC)
C) Student C (122+/-0.8oC) D) Student D (122+/-3.7oC)

8. QUESTION
The melting point of pure benzoic acid is 122°C. Data obtained by four students in a laboratory experiment are shown below. Which student’s data are the most accurate but not the most precise?
A) Student A (115+/-2.5oC) B) Student B (119+/-0.8oC)
C) Student C (122+/-0.8oC) D) Student D (122+/-3.7oC)

9. Precision (Average Deviation vs. Standard Deviation) http://en
The distribution of data (individual data points) in a set is not considered by the Average Deviation. Standard Deviation, which is the square root of the data set’s variance relative to its average (mean), is commonly used to do this.

10. Precision (Standard Deviation) http://en. wikipedia
Standard Deviation is the square root of the data set’s variance relative to its average (mean). Mathematically:
Where σ is the Standard Deviation, μ is the data’s average (mean), N is the total number of data points, and xi is the individual data point.

11. Precision & Accuracy Comparing Average & Standard Deviation (The Following Measured Data is for Volume in mL)
Standard
deviation +/
+/- 0.03
+/- 0.05 +/
(Avg. Dev)
+/- 0.04

12. QUESTION Rank the relative precision of the three sets of data:
a), b) and c). The accepted value is 8.08 mL.
Average a) b) c)
8.38
7.99
Standard
deviation a) b) c) +/
+/- 0.03
+/- 0.05
Precision: a > c > b B) Precision: b > c > a
C) Precision: a = b > c D) Precision: a > b > c

13. QUESTION Rank the relative accuracy of the three sets of data:
a), b) and c). The accepted value is 8.08 mL.
Average a) b) c)
8.38
7.99
Standard
deviation a) b) c) +/
+/- 0.03
+/- 0.05
Accuracy: a > c > b B) Accuracy: b > c > a
C) Accuracy: c > a = b D) Accuracy: a = b > c

14. Reporting Results
Visual
Audio
Tactile 36 24 28 30 26 10 16 22 19 32 23 20 34 38 35 42 18 37 27
What number best represents the respective VAT class result?
How much does the class vary in each?
Standard Deviation of each, Maximum & Minimum of each.
Average of each.
AVG
29.7
25.4
26.6
STD
5.0
6.4
6.9
Max 36 37 42
Min 20 16 10

15. Reporting Results Statistics & Rules
Chem 106 VAT Survey Results
AVG
29.7
25.4
26.6
STD
5.0
6.4
6.9
Max 36 37 42
Min 20 16 10
Should T=42 and V=10 be eliminated from the Tactile Data set and the Average recalculated?

16. Popcorn Science: Analytical Chemistry How good is the popcorn?
Industry’s Quality Standards:
Expansion
Kernel Size
Moisture Content
cm3 / g
Kernels / 10 g
Percent H2O
How would you experimentally determine these values?

17. Popcorn & Science How good is it?
Would a single trial be as good as three?

18. Popcorn & Science How good is it?
The average of 3 or more trials is common.

19. How good is it? Data for Sample X
The average of 3 or more trials is common.

20. Popcorn & Science How good is it?
Calculations:
MWVT Number: cm3/g
X Y Z ?
Kernel Size: kernels/10g ?
Percent Water: % ?
Which would you rate the best based just on these tests?