08 – Conditional Links

08 – Conditional Links

Overview

Conditional Links

• Examples

Syntax

• UserDefined Id’s
• General Introduction

Conditional Links

• Syntax Schema

Operators

• What are Operators?
• Trigger operators in rules

First Example

The CBA ItemBuilder’s concept of conditional links can be used to create various different item designs.

Examples:

• The Feedback example evaluates the selected radio button.
• The Filtering example shows how multiple links (forward and backward) can be used.

• The Answer-Unit-Correct example illustrates the use of Variables and the set()-operator in Conditional Links.

• Let’s inspect this item in the CBA ItemBuilder!

More Complex Example

• Conditional links can be sufficient to implement simple adaptive Tasks.

• Feedback (knowledge of results) is provided, for each error.
• Complete flow is illustrated here.

While this item doesn’t make too much sense from a content perspective, it illustrates how Tasks with adaptive item selection can be implemented with multiple pages of automatically scoreable closed response formats.

• Here is the flow between pages that is implemented in this example (link to cba.online.de section 4.3.6)

Naming Components (UserDefinedIDs)

UserDefinedIDs provide the reference between components in the (graphical) Page Editor and the Syntax.

• All components can be assigned to a unique id (called UserDefinedIDs).

• UserDefinedIDs are important for multiple purposes:

  • Used for scoring (e.g., Radiobutton with UserDefinedID: rb1 required for correct response)
  • Used for conditional links (i.e., conditions in links, e.g., page correct if Radiobutton with UserDefinedID: rb1 is selected)
  • Used for operators (i.e., syntax elements that change the item can refer to components using the UserDefinedIDs, e.g., set the Button with UserDefinedID: Button1 can be set frozen)
  • Used for log data (i.e, name of components in the collected log events, e.g., Button with UserDefinedID: Button1 was clicked)

There are two important requirements before we can use Conditional Links.

1. The components used in conditions need proper names. The names are called User-Defined-ID’s within the CBA ItemBuilder.

2. We need to talk about Syntax and the Syntax Editors provided within the CBA ItemBuilder.

Let’s start with the UserDefinedId’s.

Configuring UserDefinedIDs

The CBA ItemBuilder generates a placeholder for the UserDefinedIDs (a long string starting with $). Configuring UserDefinedIDs means replacing this placeholder with a meaningful identifier.

Single Components

• Properties-view in group Identification
  

Multiple Components

• Project > Edit all user defined IDs to open this dialog:

• The User-Defined-ID for single components is written directly into the Properties-view. If multiple components should be named, the menue Project contains the entry Edit all user defined IDs that can be used to define names.
• Either way: All components that should be used in Syntax need a valid UserDefinedID.

Valid UserDefinedID

The CBA ItemBuilder checks the validity and uniqueness of entered UserDefinedIds.¹

Allowed Characters (same as for page names and project names):

• Only letters, digits and underscores (_) are allowed as characters.
• Each UserDefinedId must start with a letter and it is not allowed to use a digit or underscore as the first character.
• UserDefinedIds are case sensitive and upper and lower case letters need to be distiguished.
• No spaces and blanks are allowed in UserDefinedIds.

Since the UserDefinedId is used for many different functions to connect components to syntax, it is recommended in larger CBA ItemBuilder projects to use a consistent naming scheme for all UserDefinedIds. A systematic naming schemes for the UserDefinedIds can reduce the error-proneness of scoring definitions for complex items.

1. Note that technically, the CBA ItemBuilder in Version 9.8 is a bit too carefully. If you have used an UserDefinedId A for a component, rename that component to B, the UserDefinedId A is locked until you close and re-open the project file.

General Syntax Rules – Comments

Syntax comments are recommended to ensure you and your colleagues can remember and read the meaning of specific parts of a syntax.

Why comments in syntax?

• Although no specific programming language is required, the syntax components play an important role in creating interactive items.

How to add comments to syntax?

• End of (current) line: // The rest of the line is a comment

• Sections (multiple lines possible):/* Everything within
is a comment */

What is considered as CBA ItemBuilder syntax?

• Conditional Links, Task Initialization, Finite-State Machine Rules and Hit-/Miss-Conditions for scoring.

General Syntax Rules – Auto-Completion

Syntax means keywords + UserDefinedIDs + schema.

The CBA ItemBuilder provides a Auto-Completion feature that can simplify writing syntax, as it often can suggest the appropriate keywords and possible UserDefinedIds.

How to request syntax help?

• Press Ctrl + Space (Strg + Space) in any syntax editor of the CBA ItemBuilder to see possible values in the current context (including operators and UserDefinedIDs)

General Syntax Rules – Logical Expressions

Logical Expressions

• Logical conjunction (and) and disjunction (or)
• Logical negation (not)

Boolean Data Types

• true: This is always fulfilled
• false: This is never fulfilled

UserDefinedId in Syntax

• Can evaluate to true, for instance, if a component with a particular UserDefinedId is selected.

Operators in Syntax

• Can evaluate to true, given the provided arguments.

• Syntax for conditional links and scoring is based on conditions, formulated as logical expression.

General Syntax Rules – Bracketing

The CBA ItemBuilder supports complex logical expressions. However, it is important to know that a specific formulation is necessary, that uses only pairs of conditions.

• Single conditions can be used as as, i.e., Cond1
• Two conditions need brackets, i.e., (Cond1 and Cond2)

• Logical conjunction of >= 3 conditions must be formulated as pairs:
  • ((Cond1 and Cond2) and Cond3) are two conjunction A: (Cond1 and Cond2), B: Cond3, combined to (A and B).

• Examples with negation:

  • Logical negation of a conjunction of three conditions: not ((Cond1 and Cond2) and Cond3)
  • Logical negation of a conjunction of three conditions (two with negation): not ((Cond1 and not Cond2) and not Cond3)

Conditional Links – Schema

• Conditional links are links with a dynamically selected target page.
• Multiple rules can be defined, each rule combines a page and a condition.
• The rules are evaluated one by one, until the first condition is true.

Schema:

{Page1: Condition1}  // Link to 'Page1', if 
                     // 'Condition1' is true.
{Page2: Condition2}  // Link to 'Page2', if 'Condition2' is 
                     // true (and 'Condition1' was not).

• Pages (e.g., Page1 and Page2) must exist in the current project.
• Pages can be used in multiple rules (i.e, same page in different lines).
• Order matters since condition are evaluated one sequentially.
• Nothing happens, if neither Condition1 nor Condition2 is fulfilled.
• Current page can be used as target page.

• If nothing happens, if no condition is fulfilled, why would it make sense to use the current page as target page?
• Well, we will com back to this answer later. Conditional links can be used to trigger operators without changing the current page.

Conditional Links – Assign to Component

Conditional Links are assigned as regular links.

• Step 1: Use the context-menu Link Page

• Step 2: Select Edit Condition

Conditional Links – Syntax Editor

CBA ItemBuilder Syntax Editor for Conditional Links:

• Close the syntax editor using the small x in the title bar.
• The CBA ItemBuilder will ask you to Save or Don’t Save changes:
• Note that the name (e.g., link5513717510664183471.lk_dsl is irrelevant).

Conditional Links – Tryout

Five different conditional links:

• Either target1 or target2 is shown.
• Mouse-over shows the UserDefinedIds of components.
• Note that for the button Conditional Link 4, a regular and conditional link is defined in parallel.

If regular links and conditional links are defined in parallel (see example Conditional Link 4,), the regular link is only used if no conditional link rule applies.

Conditional Links – Operator in Condition

Schema for Operator in Condition:

{Page: matches(UserDefinedId, RegularExpression)}

Example:

• This examples shows how to use Conditional Links with text input (SingleLineInputFields)
• matches(...) is like a function call (returning true or false).

• The matches(UserDefinedId,RegularExpression)-operator in the condition evaluates to true, when the Regular Expression matches the input (of the SingleLineInputField with the UserDefinedId ).

Conditional Links – Operators

Schema for Single Operator:

{Page: Condition | Operator1() }

Schema for Multiple Operators:

{Page: Condition | Operator1() Operator2() }

Schema for Multiple Operators:

{Page1: Condition1 | OperatorA() }
{Page2: Condition2 | Operator1() Operator2() }

Important:

• The terms Operator1(), Operator2() and OperatorA() are placeholders for available Operators listed on the next slide.
• Operators in Conditional Links are separated using Space (but in Finite-State Machine rules using ,).

CBA ItemBuilder Syntax defines various Operators for Conditional Links …

• Operators for Inputfields: focus, insertText
• Operators for dialog pages: openDialog, closeDialog
• Operators to change FSMs: initFSM, setFSMEvent, setFSMState
• Operators for Audio/ Video components: initMediaPlayer
• Operators for Variables: set
• Operators for components: setHidden / unsetHidden
• Operators for components with Component State: setActive / unsetActive, setFrozen / unsetFrozen
• Operators for PageAreas: setEmbeddedPage
• Operators for TextFields: setHighlightable / unsetHighlightable
• Operators for FrameSelectGroups: setMultiselect / unsetMultiselect, setNoDeselect / unsetNoDeselect, setSelectable / unsetSelectable

Operators Examples

• Frozen / Unfrozen: Is it possible to use a button?
• Change variables (e.g., count how clicks).
• Select components automatically.
• Show / Hide components completely.

• Conditional Links can execute Operators, but also require to configure a Target Page (which can be the current page).

• Most often, Operators will be triggered from the Finite-State Machine (see session 11).

Summary

Helpful to remember:

• Conditional Links are useful for different purposes, including Feedback or simple Adaptivity.
• Conditional Links use a domain-specific language (i.e., a simple syntax).
• The link between components and syntax is established using User Defined IDs (names for components that are unique within a CBA ItemBuilder Project File).

Additional tips:

• Operators allow to change items during runtime.

Important:

• Logical expressions in the CBA ItemBuilder need Bracketing (i.e., to create pairs).