Demand characteristics can threaten internal validity because the results can be explained by reactivity instead of the treatment conditions correlate with those that threaten external validity may be specific to the experimenter who has the expectations may not generalize to situations where demand characteristics are different

This problem has been solved! see the answerwhich of the following statements is correct? the consumer price index is a measure of the overall level of prices, whereas the gdp deflator is not a measure of the overall level of prices. if, in the year 2011, the consumer price index has a value of 123.50, then the inflation rate for 2011 must be 23.50 percent. compared to the gdp deflator, the consumer price index is the more common gauge of inflation. the consumer price index and the gdp deflator reflect the goods and services bought by consumers equally well.