Which statement from a newspaper article refers to the consumer price index
(cpi)?

"The average cost of groceries has increased 10 percent since last year" statement from a newspaper article refers to the consumer price index  (CPI).

Explanation:

A Consumer Price Index "calculates increases in the price level of a weighted average consumer goods and services market basket purchased by households". It is usually calculated and published on a monthly and yearly basis by a country's Bureau of Economic Analysis and Statistics.

For an instance the Consumer Price Index for "All Urban Consumers (CPI-U)" rose 2.0 per cent from April 2018 to April 2019, the largest increase over the year since the 12-month period ending November 2018.

i believe the answer is:   psychological  experiment

in this experiment, wilhelm wundt became the first person that implement scientific method in analyzing the pyschological phenomenon.

due to this result, wilhelm wundt also able to make psychology to be acknowledged as a separate scientific field from biology.