In index numbers, one figure is selected at 100% and all others are expressed as percentages of that figure. In this chart the average for the years from 1923 through 1925 was selected as the base figure or 100%.

1929 1930 1931 1932 1933 1934 1935 1936

Federal Reserve Bank of New York, "Monthly Review," March 1, 193 7. SCALE .7

B. Indexes of Volume of Agricultural and Non-Agricultural Exports in the United States from 1929 to 1936. 1923.25 Average Equals 100%.

It is better to have both the 100% line and the zero line heavier than the others in an index-number chart.

GRAPHIC PRESENTATION

-i -- I -- r--i -- I -- I -- I -- I -- i -- I -- r

-I -- I -- I -- \ -- \ -- I -- I -- I -- ' -- I -- r- Price Barometer of Profits

(1910= 100)

Income

Alexander Hamilton Institute. "Business Conditions Weekly." July 2J. 1<»38.

A. Price Barometer of Profits in the United States from January 1937 to July 1938.

The crossing of two lines often creates areas which can be labelled. Compare the shadmg of these two areas with 283.

* SEASONAL AVERAGE PRICE TO CKOIVERS

U S Department of ARricuIture. Bureau of ARricultural Economics SCALE b

B. Comparison of the Indexes of Production, Total Value, and Price of Seventeen Vegetables for Fresh Market in the United States from 1919 to 1936.

In curve charts, when a number of curves are plotted on the same grid and when a number of curve patterns are used, it is better to have the curves labelled as they are here than to have a boxed legend or key to identify them.