STATISTICS ELEMENTARY MARIO F. TRIOLA Section 1-3 Uses and Abuses of Statistics MARIO F. TRIOLA EIGHTH EDITION

Uses of Statistics Almost all fields of study  benefit from the application  of statistical methods page 11 of text

Abuses of Statistics Bad Samples

Definitions self-selected survey (or voluntary response sample) one in which the respondents themselves decide whether to be included One of the most common methods of bad sampling

Abuses of Statistics Bad Samples Small Samples Loaded Questions Misleading Graphs

Figure 1-1 Salaries of People with Bachelor’s Degrees and with High School Diplomas $40,500 $40,500 $40,000 $40,000 35,000 30,000 $24,400 30,000 20,000 $24,400 page 11 of text Graphs whose vertical scales do not start at 0 will give a misleading representation of the differences in heights of the bars. 25,000 10,000 20,000 Bachelor High School Degree Diploma Bachelor High School Degree Diploma (a) (b)

We should analyze the numerical information given in the graph instead of being mislead by its general shape.

Abuses of Statistics Bad Samples Small Samples Loaded Questions Misleading Graphs Pictographs

Double the length, width, and height of a cube, and the volume increases by a factor of eight page 14 of text Figure 1-2

Abuses of Statistics Bad Samples Small Samples Loaded Questions Misleading Graphs Pictographs Precise Numbers Distorted Percentages Partial Pictures

“Ninety percent of all our cars sold in this country in the last 10 years are still on the road.”

Abuses of Statistics Bad Samples Small Samples Loaded Questions Misleading Graphs Pictographs Precise Numbers Distorted Percentages Partial Pictures Deliberate Distortions