Here's how the story was covered by ABCnews.
The researchers visited a sample of fast food restaurants in the Boston area, found tables in which parents were sitting with kids, and made notes of the parents' and children's behavior. One of the major findings was the degree to which the parents were engaged by their mobile devices:
Parents in 40 of the 55 families observed were absorbed in their mobile devices, according to the study.
a) What kind of claim is the journalist apparently making above? What is/are the variable(s) in the claim?
b) How would you ask about the external validity of the study?
The researchers observed both parents and children:
... almost a third of the parents used their devices continuously throughout their meal....Some children appeared unaffected and ate their meals in silence. Other children were more provocative, with one set of siblings singing “Jingle bells, Batman smells” to get their dad’s attention.
c) How would you ask about the construct validity of these measures of parental and child behavior?
There is an inconsistency in the journalist's story. Although the headline of the study makes an association claim, "Parents on smartphones ignore their kids, study finds," the body of the story reports that:
The degree to which the device was used, however, did not necessarily directly relate to the way in which the child reacted, according to the study.
Indeed, if you read the original journal article in Pediatrics, you'll see that the real study did not report much evidence of associations between parental behavior and child behavior.
a) This line about "40 out of 55 families" is a frequency claim--it seems to simply be documenting "what parents do" when eating in restaurants with children.
b) You'd want to ask "how did they choose these 55 families to observe? Did they use a random sampling/probability sampling technique?" If they sampled families based on convenience, it would be difficult to infer that the same proportion of all American families show these cell phone habits.
You might also ask about the degree to which the setting generalizes. Does parental behavior in restaurants generalize to their behavior at home, or to other settings where they are with the kids?
c) To ask about construct validity, you'd want to ask about how well the coders were trained. Did the coders have good inter-rater reliability? Did they follow a codebook? What behaviors did they decide to code and how well did they code them?
Thanks to my colleague Agnes Ly for this story idea!