Compare the upper chart with Fig. 145

In biological work the number of observations taken is ordinarily sufficient to permit drawing a smooth curve to represent the general law, after a chart drawn with numerous straight lines has been made by the method used in Fig. 143. It would not be desirable to draw a smooth curve in the case of Fig. 143, as the smooth curve would be misleading because of the small number of observations made. For most business problems, and in many problems actually in the field of statistics, the laws which affect frequency are so indefinite

FREQUENCY CURVES

and the number of observations so limited that it is much better to use the straight-hne method of Fig. 143 than to attempt to make a smooth curve. Sometimes a smooth curve may only mislead the reader, making the chart appear very accurate when in reality the data were so crude that only the roughest approximation is possible. Fig. 144 is copied from the Census Atlas for the 1900 Census. In the Atlas, colors were used for the different areas which must be represented here by cross-hatching. Though these illustrations hold some very valuable and interesting information, the information is contained

Per CenT

lOO

^"^^^

"^^

\

ARRIED

i

^y

-y^

^^

-^'^^;-

"*"''*'"^^..^^^

\

\/

/

^^t^

) "^

\

/\J

/

\

.>^^

\

5?/

.f.C3

y

1 J

/

^N

^i)^^-^

-,p-0_^,x--^

^, J

1/

■*^><^

^"^i^^

(^

---

iri:

«_=^

««:r=r«.

under

15-19 25-29