identify the sample technique and describe the advantages and limitations of each technique.

a)The names of all 1,000 children are placed into a computer database. The computer is then instructed to randomly select 100 names. These children and their parents are then contacted.

b)The names of all 1,000 children are placed into a computer database and organized by grade (6th, 7th, and 8th). The computer is then instructed to randomly select 35 names from each of the three grades. These children and their parents are then contacted.

c)The researcher knows one of the middle school teachers, and the teacher volunteers her 35 students for the study. These children and their parents are then contacted.

d)Using middle-school directory, the researcher selects the first twenty 6th grade boys, the first twenty 6th grade girls, the first twenty 7th grade boys, the first twenty 7th grade girls, the first twenty 8th grade boys, and the first twenty 8th grade girls. These children and their parents are then contacted.