Numerical tolerance determines whether student answers that are close to the answer key
are counted as correct. In WebAssign, numerical tolerance can be set in four different places to
override the default numerical tolerance of ±2%.
Note: When significant figure checking is turned on, questions that specify significant figures
in the answer key use a different tolerance setting than is discussed here.
By default, new assignments do not override the class settings for numerical tolerance.
Tip: To change this default behavior, create an assignment template that overrides
the class settings and set it as your default template.
You can set numerical tolerance values for a class, an assignment,
or for a specific question on an assignment. These tolerances override each other, the tolerance
set in the question code, and the default WebAssign tolerance.
The actual tolerance that is used is the tolerance with the highest priority in the following
list:
- Tolerances set in the assignment for specific questions override all other tolerances.
- Tolerances set in the assignment or assignment template for the assignment as a whole
override tolerances set by 3-5.
- Tolerances set in your class settings override tolerances set by 4 and 5. The default class
settings do not specify tolerance.
- Tolerances set in the question code override the WebAssign default tolerance. A tolerance of
0 is almost always specified for mathematics textbook questions, textbook questions requiring
students to enter fractions, and textbook questions requiring simple computation of
integers.
- The WebAssign default tolerance of ±2% is used when no other tolerances are set. This is a
standard used by many professional scientists and engineers, and ensures that the answer is
correct to three significant figures.
Important: Changing numerical tolerance settings can result in granting credit for
incorrect responses, as in the following examples:
- When asking about the speed of a relativistic electron, a 1% tolerance would allow students
who round a response of 0.99975c up to 1.00c to be marked correct.
- When asking students to determine the area of a rectangle that is 32.5 m by 3 m, the exact
answer of 97.5 m2 is correct, not, for example, 98 m2 or 100
m2.
If you do change numerical tolerance settings, test every question carefully to ensure
that your students receive credit for all correct responses and do not receive credit for
incorrect responses.
You can set numerical tolerance as a non-negative number of units, or as
a percentage of the answer key.
|
Key value
|
Tolerance setting
|
Responses scored as correct
|
|
120
|
2% (default)
|
117.6-122.4
|
|
120
|
10 units
|
110-130
|
For questions with multiple parts, any tolerances that you set in the
assignment or class settings apply to all parts of the question. Only the question author can
set different tolerances for different parts of a multiple-part question.
If you change these settings after students have submitted responses, you
may need to rescore your assignment. For more information about rescoring, see Rescore Assignments