CAT Parameters Screen

Fields: CAT Parameters Screen

Here is information about the fields (features) on the CAT Parameters screen.

The name of the instrument.

A label displaying the IRT Model assigned to a CAT instrument on the Instrument Properties page.

Calibration Sample

A drop list which allows you to select the calibration sample, i.e. classification of the statistics (item parameters), which should be used during item administration.

Selection Method

This feature is used to designate the selection method (criterion of item selection) for use in item administration.

Selection Methods currently available are:

This is an optional field which may be used to override the standard means of first item selection.

There are two options:

If you do not make a selection from this field the first item will be determined based upon item information entered on the Item Statistics pages.

You may select a theta value by which the first item should be selected. To do this select Theta from the First Item drop list, a Theta field will then appear so that you may enter a theta value.

This field has a minimum value of -9.00 and a maximum value of 9.00.

You may select a particular item within your instrument to be the first item. To do this select Item ID from the First Item drop list, an Item ID drop list will then appear so that you may select which item should be displayed to participants first.

Prior Distribution: Mean

Enter the prior distribution mean of likelihood estimates. The default value is 0.

Prior Distribution: Standard Deviation

Enter the prior distribution standard deviation of likelihood estimates. The default value is 1.

This field has a minimum value of 0.10 and a maximum value of 10.00.

Number of Items: Minimum

Enter the minimum number of items that should be administered to participant. The default value is 4.

Once a CAT instrument has administered the number of items here and reached the standard error value set on the CAT Parameters page, the CAT engine will stop administering items from this instrument.

This field has a minimum value of 1 and a maximum value of 999.

Number of Items: Maximum

Enter the maximum number of items that should be administered to participant. The default value is 12.

Once a CAT instrument has administered the number of items here, the CAT engine will stop administering items from this instrument regardless of the standard error value set on the CAT Parameters page.

This field must be greater than the number of items: minimum field.

Enter the standard error that should be reached before the CAT administration stops. The default value is 0.3.

Once CAT instrument score calculations have reached the standard error value entered here and the minimum number of items has been administered, the CAT engine will stop administering items from this instrument.

This field has a minimum value of 0.00 and a maximum value of 0.30.

Theta: Lower Bound

his field limits the theta’s rate of change by defining the lower bound of the growth rate. The default is -4.

This field has a minimum value of -9.00 and a maximum value of 9.00

Theta: Upper Bound

This field limits the theta’s rate of change by defining the upper bound of the growth rate. The default is 4.

This field has a minimum value of -9.00 and a maximum value of 9.00. Also, the upper bound theta value must be greater than the lower bound theta value.

This field is a theta increment which is a component for measuring the rate of change The default is 0.1.

This field has a minimum value of 0.005 and a maximum value of 0.25.

Constant: Location

This field has a minimum value of -5.00 and a maximum value of 5000.

Constant: Dispersion

This field has a minimum value of 0.001 and a maximum value of 1000.

Does not save any changes.

Reset to Default Parameters

Reverts field values back to default.

Fields: CAT Parameters Screen Here is information about the fields (features) on the CAT Parameters screen.
Instrument	The name of the instrument.
IRT Model	A label displaying the IRT Model assigned to a CAT instrument on the Instrument Properties page.
Calibration Sample	A drop list which allows you to select the calibration sample, i.e. classification of the statistics (item parameters), which should be used during item administration.
Selection Method	This feature is used to designate the selection method (criterion of item selection) for use in item administration. Selection Methods currently available are: · MLWI · MPWI · MEPV
First Item	This is an optional field which may be used to override the standard means of first item selection. There are two options: · Theta · First Item If you do not make a selection from this field the first item will be determined based upon item information entered on the Item Statistics pages. Theta: You may select a theta value by which the first item should be selected. To do this select Theta from the First Item drop list, a Theta field will then appear so that you may enter a theta value. This field has a minimum value of -9.00 and a maximum value of 9.00. Item: You may select a particular item within your instrument to be the first item. To do this select Item ID from the First Item drop list, an Item ID drop list will then appear so that you may select which item should be displayed to participants first.
Prior Distribution: Mean	Enter the prior distribution mean of likelihood estimates. The default value is 0.
Prior Distribution: Standard Deviation	Enter the prior distribution standard deviation of likelihood estimates. The default value is 1. This field has a minimum value of 0.10 and a maximum value of 10.00.
Number of Items: Minimum	Enter the minimum number of items that should be administered to participant. The default value is 4. Once a CAT instrument has administered the number of items here and reached the standard error value set on the CAT Parameters page, the CAT engine will stop administering items from this instrument. This field has a minimum value of 1 and a maximum value of 999.
Number of Items: Maximum	Enter the maximum number of items that should be administered to participant. The default value is 12. Once a CAT instrument has administered the number of items here, the CAT engine will stop administering items from this instrument regardless of the standard error value set on the CAT Parameters page. This field must be greater than the number of items: minimum field.
Standard Error	Enter the standard error that should be reached before the CAT administration stops. The default value is 0.3. Once CAT instrument score calculations have reached the standard error value entered here and the minimum number of items has been administered, the CAT engine will stop administering items from this instrument. This field has a minimum value of 0.00 and a maximum value of 0.30.
Theta: Lower Bound	his field limits the theta’s rate of change by defining the lower bound of the growth rate. The default is -4. This field has a minimum value of -9.00 and a maximum value of 9.00
Theta: Upper Bound	This field limits the theta’s rate of change by defining the upper bound of the growth rate. The default is 4. This field has a minimum value of -9.00 and a maximum value of 9.00. Also, the upper bound theta value must be greater than the lower bound theta value.
Increment	This field is a theta increment which is a component for measuring the rate of change The default is 0.1. This field has a minimum value of 0.005 and a maximum value of 0.25.
Group Size	The default is 1.
Constant: Location	The default is 0. This field has a minimum value of -5.00 and a maximum value of 5000.
Constant: Dispersion	The default is 1. This field has a minimum value of 0.001 and a maximum value of 1000.
Save	Saves changes.
Cancel	Does not save any changes.
Reset to Default Parameters	Reverts field values back to default.