This CNN story reports on research presented at an academic conference for Pediatrics. According to the conference presentation, "A study found that the more time children between the ages of six months and two years spent using handheld screens such as smartphones, tablets and electronic games, the more likely they were to experience speech delays." According to this description, the two main conceptual variables in the study are "time spent using a handheld screen" and "speech delay." Read on to find out how each variable was operationalized: "In the study, which involved nearly 900 children, parents reported the amount of time their children spent using screens in minutes per day at age 18 months. Researchers then used an infant toddler checklist, a validated screening tool, to assess the children's language development also at 18 months. They looked at a range of things, including whether the child uses sounds or words to get attention or help and puts words together, and how many words the child uses."

According to the text, how did the study operationalize the variable, speech delay?

How did they operationalize time spent using a handheld screen?

Do you think this was a valid measure? Why or why