Question

Based on the following information, calculate the specificity.

A screening test was used with 224 children ages 3-5 years attending a subsidized day care to determine if any of the children had speech/language delays using the ASQ (Ages and Stages Questionnaire). The same children were also given a clinical evaluation by a Speech and Language Pathologist (SLP) which is the gold standard for diagnosis of speech/language delays.

The ASQ found that 75% of the children had a speech/language delay. Of those children, the SLP found that 122 chidlren actually had a speech/language delay. The SLP found an additional 8 children had a speech/language delay who were not identified as having one by the ASQ.

The specificity is [specificity].

(Answers should be entered as a numeric value round to 1 decimal place: example XX.X. Do not enter the % symbol. Use correct rounding procedures)

Answer 1

-Based on the above given information specificity is calculated as-

The specificity is calculated as the number of non-diseased correctly classified divided by all non-diseased individuals.

Specificity = True negatives x 100    Total non-diseased individuals

    (in percentage)

OR Specificity = True negatives ​​​        True negatives +False positives

(in decimals)

Here, True negative children are rest 25% children (56 in number) but SLP founded additional 8 children as speech/language delay, so the Total True negatives(56-8) are 48 in number

Then,false positive are 46 in number that is children who are tested positive by ASQ but found negative by SLP( that is 168-122=46).

so, Specificity = 48   48+46

= 48   94

= 0.51 (rounded to one decimal place)

= 0.5

Thus 0.5 is the specificity.