Likert scale

1.     The scale contains several items.
2.     Response levels are arranged horizontally.
3.     Response levels are anchored with consecutive integers.
4.     Response levels are also anchored with verbal labels which con note
more-or-less evenly-spaced gradations.
5.     Verbal labels are bivalent and symmetrical about a neutral middle and
6.     In Likert's usage, the scale always measures attitude in terms of level of agreement/disagreement to a target statement .
Criterion 5 usually means there is an odd number of response levels. Typically the number is 5, though sometimes 7, 9, or 11 levels are used.
Common Error 1
A Likert scale is never an individual item; it is always a set of several items, with specific format features, the responses to which are added or averaged to produce an overall score or measurement.
There are two of the biggest and most common confusions people make.

A single item, even if formatted exactly as one of Likert's items, is not a Likert scale.

Likert items

If features 2 through 5 above are all present, we may justifiably call them Likert items. If only 2 through 4 are present, we might call them Likert-type items instead.
How do you feel about the President's performance in domestic affairs?
Strongly     Somewhat                     Somewhat     Strongly
disapprove   disapprove     Neutral       approve      approve
   1                      2                   3                 4                  5
Example 2: A Likert item
Consider the example above. Here we meet all criteria 2 - 5. It seems fair to call this a Likert item, even though it doesn't refer to agreement/disagreement to a target statement.
The following, then, would be considered a Likert-type item.                 
How often do you go out to see a movie?
Never   Sometimes  Average    Often     often
  1                   2               3            4           5
Example 3: A Likert-type item
Here the response levels are not bivalent: the lower terminus is merely "Never". There is no exact opposite of "Very often". Yet the categories are reasonably interpretable as evenly spaced, especially when associated with consecutive integers in an evenly-spaced printed format. The label for level 3, "Average" clearly denotes centrality of this response category.
Common Error 2
This is not a Likert-scale, a Likert item, or a Likert-type item:
     How often do you smoke cigarettes?


        1.  Never
        2.  Once in a while
        3.  1-5 per day
        4.  More than 5 per day.

This is simply an item with ordered response levels, or an ordered-category item.
This is so even if the item is one of several that will be combined to form an aggregate scale. In this case, one simply has a summated rating scale comprised of several ordered-category variables.
The method of construction of a Likert type scale-
Researcher gathers a large number of statements which clearly indicate favourable or unfavourable attitude towards the given issue.
·         Piloting
·         Validity test
·         Content validity

Scoring and analysis

After the questionnaire is completed, each item may be analyzed separately or in some cases item responses may be summed to create a score for a group of items. Hence, Likert scales are often called summative scales .
After the Likert scale is administered to subjects, the response must be scored. Typically the responses are scored in such a way that endorsement of positively worded statements and nonendorsement of  negatively worded statements are scored higher
-Construction is less cumbersome
-It supplies more precise and definite response towards an issue.
-Permits the revelation of several  (5) degrees of agreement or disagreement
-Has broader areas of reference as any item empirically consistent with the statement may be included. 
-The judgment on the basis of total score , which  is estimated by calculating mean or median , is not scientific. The total score value may be same in many cases but attitude may  be different.
-No objective basis for expressing different degrees of agreement or  disagreement.


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