In order to prevent the researcher's expectations from influencing study participants, a(an) design is used

Double-blind

Explanation:

A double-blind study is a study in which neither the participants nor the experimenters know who the control group is. This is done in order to prevent the researcher's expectations from influencing the study participants. In this type of experiment, the researchers do not know who is receiving a placebo, so their bias is taken out of the equation.

the federal government of the united states was established by the constitution. us is a presidential republic. the president is head of state, head of government and of a two party legislative and electoral system. the supreme court balances the powers of the federal and the state government. yhe executive branch is headed by the oresident. there are two chambers of congress, the senate and the house of representatives. judicial power is exercised by the judicial branch (or judiciary), comprised of the supreme court and lower federal courts. the judiciary's function is to interpret the   constitution as well as the federal laws and regulations.

many citizens are in danger of contracting a food-borne illness.

more people are living with chronic illnesses.

pathogens are becoming stronger and harder to defeat.

edge nuity