A researcher is comparing three new formulas for
grass killer. To conduct the experiment, the researcher
purchases 30 pieces of sod from a local vendor and
selects the treatment groups by placing slips of paper
numbered 1-30 in a hat. To make three groups for the
three formulas, the researcher randomly selects 10
numbers, making sure to mix the slips between each
selection, to get the formula 1 group. Then the
researcher selects 10 more numbers to get the formula
2 group. The remaining 10 numbers make up the
formula 3 group.
Which component is missing from the researcher's
process?
The researcher did not randomly pick the vendor.
The researcher did not randomly pick the 30 pieces
of sod.
The researcher did not assign a treatment to each
group of sod.
The researcher did not label the pieces of sod
before randomly selecting them.