﻿ Remove an item

# Remove an item.

It sometimes happens that users will be Lertapping along, humming their favourite tune, and suddenly wish that they could omit a single item or two from a subtest, just to see how that might change things (such as the value of coefficient alpha).  There are a variety of ways in which this may be accomplished.

The most obvious way is to make a new *col card.

For example, consider these CCs cards:

*col (c28-c37)

*sub aff, title=(Comfort)

*pol +---- ++--+

Now, suppose it was found that the item in column 36 was not correlating well with the others, was serving to bring down the subtest's reliability figure (coefficient alpha), or for some other reason had to be removed from the subtest.  The following *col card will do the job:

*col (c28-c35, c37)

But this isn't the only change required.  The *pol card must be changed too -- we've taken an item out of the subtest, and must remove the corresponding plus (+) or minus (-) sign from the *pol card:

*col (c28-c37)

*sub aff, title=(Comfort)

*pol +---- ++-+

An easier way to take the item out is to make use of a special form of the *mws card:

*col (c28-c37)

*sub aff, title=(Comfort)

*pol +---- ++--+

*mws c36, *

The *mws card above has a single asterisk after the column number.  This is a special form of the *mws card, used to remove an item.  This special use of the *mws card eases the task of taking items out of a subtest -- there's no requirement to make corresponding changes to other cards, such as the *pol card.

There's another way to remove items from affective subtests: use asterisks on the *alt card, as shown in the example below:

*col (c28-c37)

*sub aff, title=(Comfort)

*pol +---- ++--+

*alt 55555 555*5

The *alt card above tells Lertap that the penultimate item (second to last) is to be excluded from the subtest.

The examples above are based on an affective subtest, but the special uses of the *mws and *alt cards shown here also apply to cognitive subtests.  Consider this example:

With all items:

*col (c3-c27)

*sub res=(A,B,C,D,E,F), Title=(Knwldge)

*key AECAB BEBBD ADBAB BCCCB BABDC

*alt 35423 35464 54324 43344 45546

Using *mws to remove the sixth item:

*col (c3-c27)

*sub res=(A,B,C,D,E,F), Title=(Knwldge)

*key AECAB BEBBD ADBAB BCCCB BABDC

*alt 35423 35464 54324 43344 45546

*mws c8, *

Using *alt to remove the sixth item:

*col (c3-c27)

*sub res=(A,B,C,D,E,F), Title=(Knwldge)

*key AECAB BEBBD ADBAB BCCCB BABDC

*alt 35423 *5464 54324 43344 45546

SAQ: would the example immediately above actually work?  If I copied the 16 lines and pasted them into a CCs worksheet, would they actually work?  Yes.  This example is just a straightforward job with three subtests.  The lines which do not begin with an asterisk are comments, and are not processed by Lertap.

Finally, our examples here have discussed removing a single item from a subtest.  To remove more than one item, follow the same pattern.  The examples below will remove two items from their respective subtests:

*col (c28-c37)

*sub aff, title=(Comfort)

*pol +---- ++--+

*mws c29, *

*mws c36, *

*col (c3-c27)

*sub res=(A,B,C,D,E,F), Title=(Knwldge)

*key AECAB BEBBD ADBAB BCCCB BABDC

*alt 35423 *5464 54324 4*344 45546

Note: the *exc card makes it somewhat easier to remove, or "exc"lude, items.  Please to see the following topic.