In the next analysis phase the authors assessed content validity of the 6th through 12th grade
survey through the use of subject matter experts. Three subject matter experts rated items in the
four attitudes toward science, engineering, math, and 21st century skills scales as “Essential,”
“Useful but not Essential,” or “Not Necessary.” Using the collected data, the researchers
calculated Lawshe’s content validity ratio (CVR) for each item. Ranging from negative one to
positive one, a positive CVR indicates that over half of the subject matter experts rated the item
as “Essential.” Within the attitudes toward engineering scale, items that were specific (e.g. “At
the science museum, I like the exhibit on robotics”) tended to have a lower CVR than items that
were more generic (e.g. “Engineering skills will allow me to improve society”). The attitudes
toward math, science, and 21st century skills constructs received positive ratings overall