Purdue University - Department of Computer Science - Formula Grade Item

Use the Formula Editor to define a formula that calculates a grade item’s value based on other grade items. When you create a formula, you specify which grade items you want included in the formula and the relationships between them. An example of a simple formula is one that calculates the sum of a number of grade items. A more complicated formula is one that drops the minimum or maximum value from a set of grade items.

The Formula Editor is available on the New Item page and Edit Item page for Formula grade items, and the Edit Calculated Final Grade page and Edit Adjusted Final Grade page for the Formula grading system.

## Access the Formula Editor

1. On the Manage Grades page, click the name of a formula grade item you wish to edit.
2. Click   Edit Using the Formula Editor.

## Key Grades Formula Editor components

### 1. Formula area

The Formula Area is where the formula text is displayed. The equals sign (=) at the start of the formula cannot be deleted. A cursor shows your position in the formula. Click in the formula area to position the cursor.

### 2. Cursor placement

The cursor placement icons are used to move the cursor forwards and backwards in the formula. You can also move the cursor by clicking on the new location with your mouse. There are four options:

•  Move cursor to start of formula.
•  Move cursor to end of formula.
•  Move cursor back one element.
•  Move cursor forward one element.

Use the   Grade Item  drop-down list to view what grade items you can insert as a parameter in your formula. You can insert Numeric, Pass/Fail, Selectbox, and Formula type grade items. You cannot reference the formula grade item you are defining (this avoids a circular reference) or a final grade.

Use the   Grade Item Value  drop-down list to view the values associated with the grade item you want to use in the formula. There are three options:

• Points Received   The grade the user achieved. E.g., 7 (out of 10 points).
• Max Points   The maximum points available for the grade item. E.g., 10 points.
• Percent   The percent grade the user achieved. E.g., 70%.

Click   Insert  to insert the selected grade parameter in the formula.

### Insert a grade item parameter in a formula

2. Select the  Grade Item Value  you want to use in the calculation.
3. Click  Insert.
NOTES
• For the weighted system, category and grade item weights are ignored in formula calculations.
• Calculated grade items cannot be inserted.

### 4. Functions

The   Function  drop-down list contains a list of functions that you can use in your calculation formula:

• MAX  Calculates the maximum (largest) value in a set of values.
• MIN  Calculates the minimum (smallest) value in a set of values.
• SUM  Calculates the sum (total) of a set of values.
• AVG  Calculates the average for a set of values by adding all the values and dividing by the total number of values.
• IF  Operates as a Boolean statement that returns either the value set as true or as false. You must define the condition (Boolean statement), true (then) value, and false (else) value.

• NOT  Operates as a Boolean statement that returns the value set as true if the condition is false and as false if the condition is true.

NOTES
• You can embed functions within functions.
• The   StartNext Term, and End options are used to define elements of a function:
• Start Starts the function selected in the   Function  drop-down list with an opening bracket ({).
• Next Term Inserts a comma to separate grade items or parts of a Boolean statement.
• End Ends the function with a closing bracket (}).

### Insert a function in a formula

1. Select a  Function.
2. Click Start.
3. Enter a parameter.
4. Click Next Term  to add another parameter or use the numeric keys and operators to define a condition.
5. Click End  when you are done adding parameters and conditions.

### 5. Numeric keys and operators

The right area of the Formula editor contains a number of operators and a numeric key pad to build your formula. These operators are usually used in conjunction with at least one grade item.

### 6. Backspace and clear

The   Backspace  and   Clear  options let you delete parts of your formula to make changes.

• Backspace  Deletes the element to the left of the cursor.
• Clear  Deletes the entire formula.

### 7. Cancel

The   Cancel  button exits the Formula Editor without saving your changes.

### 8. Insert

The   Insert  button validates your formula and applies it to the grade book item or final grade you are working on. If your formula is invalid, you receive an error message and your cursor moves to the point in the formula that caused the error. The error type displays in red above the formula. See   Grades Formula Editor validation errors  for a list of potential errors.

### 9. Validate

The   Validate  option checks if your formula conforms to standard formula grammar. If your formula is valid, a confirmation message displays. If your formula is invalid, you receive an error message and your cursor moves to the point in the formula that caused the error. The error type displays in red above the formula. See   Grades Formula Editor validation errors  for a list of potential errors.

### 10. Preview

The Preview option lets you check how your formula will calculate grades for the first ten users in your user list. Click   Close  when you are finished viewing the grades. If your formula is invalid, you cannot preview grades.

## Grades Formula Editor validation errors

#### Examples

Unexpected [token_type]

e.g., Unexpected operator

The formula contains a function component in an unexpected location

= 5=/1

= (5+1)2

Unbalanced parentheses

The formula contains an opening or closing bracket without a corresponding bracket

= 5+1)

Missing end of function

The formula contains an unclosed function

= SUM{[Item1.Points], [Item2.Points]

Unexpected function end

The formula contains a closing bracket for a function that does not relate to a function

= [Item1.Points]/2}

Invalid number of operator parameters

The formula contains an invalid number of operator parameters

= [Item1.Points] +

Invalid number of function parameters

The formula contains an invalid number of function parameters

= SUM{}

= IF{[Item1.Points]<2,5}

Numeric value expected

A Boolean statement or operator was entered in place of a numeric value

= IF{5<2,1 OR 1,4}

= SUM{1 = 2,3,4}

Boolean value expected

A Boolean statement was not entered for a condition

= IF {MIN{4,5},100,0}

= NOT{4}

Invalid terminal

The formula contains an incorrectly used terminal

= [Item1.Points] + 3.2.5

Scenario 1: Give users who achieved over 75% on all grade items in a category 100% for the category.

`= IF {MIN{[Week1.Percent],[Week2.Percent],[Week3.Percent]} < 75, 0, 100}`

Scenario 2: Drop the lowest two grades in a set of three grades

`= SUM{[G1.PointsReceived],[G2.Points Received], [G3Points Received]} - MIN{[G1.PointsReceived],[G2.Points Received]} - IF{MIN{[G2.Points Received], [G3Points Received]} = MIN{[G1.PointsReceived],[G2.Points Received]},MIN{[G1.PointsReceived],[G3.Points Received]}, MIN {[G2.PointsReceived],[G3.Points Received]}}`

Scenario 3: Fail users who receive less than 60% on either their midterm or final exam.

`= IF {MIN{[Midterm.Percent],[Final.Percent]} < 60, 0, SUM {[A1.Percent],[A2.Percent],[G1.Percent],[G2.Percent],[Midterm.Percent],[Final.Percent]}}`

Last Updated: Sep 15, 2020 12:08 PM

Department of Computer Science, 305 N. University Street, West Lafayette, IN 47907

Phone: (765) 494-6010 • Fax: (765) 494-0739