02 April 2006

Herbert F Spirer - Collected Quotes

"Clearly, the mean is greatly influenced by extreme values, but it can be appropriate for many situations where extreme values do not arise. To avoid misuse, it is essential to know which summary measure best reflects the data and to use it carefully. Understanding the situation is necessary for making the right choice. Know the subject!" (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"'Garbage in, garbage out' is a sound warning for those in the computer field; it is every bit as sound in the use of statistics. Even if the “garbage” which comes out leads to a correct conclusion, this conclusion is still tainted, as it cannot be supported by logical reasoning. Therefore, it is a misuse of statistics. But obtaining a correct conclusion from faulty data is the exception, not the rule. Bad basic data (the 'garbage in') almost always leads to incorrect conclusions (the 'garbage out'). Unfortunately, incorrect conclusions can lead to bad policy or harmful actions." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"Graphic misrepresentation is a frequent misuse in presentations to the nonprofessional. The granddaddy of all graphical offenses is to omit the zero on the vertical axis. As a consequence, the chart is often interpreted as if its bottom axis were zero, even though it may be far removed. This can lead to attention-getting headlines about 'a soar' or 'a dramatic rise (or fall)'. A modest, and possibly insignificant, change is amplified into a disastrous or inspirational trend." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"If you want to show the growth of numbers which tend to grow by percentages, plot them on a logarithmic vertical scale. When plotted against a logarithmic vertical axis, equal percentage changes take up equal distances on the vertical axis. Thus, a constant annual percentage rate of change will plot as a straight line. The vertical scale on a logarithmic chart does not start at zero, as it shows the ratio of values (in this case, land values), and dividing by zero is impossible." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"In analyzing data, more is not necessarily better. Unfortunately, it is not always possible to have one uniquely correct procedure for analyzing a given data set. An investigator may use several different methods of statistical analysis on a data set. Furthermore, different outcomes may result from the use of different analytical methods. If more than one conclusion results, then an investigator is committing a misuse of statistics unless the investigator shows and reconciles all the results. If the investigator shows only one conclusion or interpretation, ignoring the alternative procedure(s), the work is a misuse of statistics." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"It is a consequence of the definition of the arithmetic mean that the mean will lie somewhere between the lowest and highest values. In the unrealistic and meaningless case that all values which make up the mean are the same, all values will be equal to the average. In an unlikely and impractical case, it is possible for only one of many values to be above or below the average. By the very definition of the average, it is impossible for all values to be above average in any case." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"It is a major statistical sin to show a graph displaying a variable as a function of time with the vertical (left-hand) scale cut short so that it does not go down to zero, without drawing attention to this fact. This sin can create a seriously misleading impression, and, as they do with most sins, sinners commit it again and again." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"It is a misuse of statistics to use whichever set of statistics suits the purpose at hand and ignore the conflicting sets and the implications of the conflicts." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"Jargon and complex methodology have their place. But true professional jargon is merely a shorthand way of speaking. Distrust any jargon that cannot be translated into plain English. Sophisticated methods can bring unique insights, but they can also be used to cover inadequate data and thinking. Good analysts can explain their methods in simple, direct terms. Distrust anyone who can't make clear how they have treated the data." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"Know the subject matter, learn it fast, or get a trustworthy expert. To identify the unknown, you must know the known. But don't be afraid to challenge experts on the basis of your logical reasoning. Sometimes a knowledge of the subject matter can blind the expert to the novel or unexpected." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"Percentages seem to invite misuse, perhaps because they require such careful thinking." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"There is no shortage of statistical methods. Elementary statistics textbooks list dozens, and statisticians constantly develop and report new ones. But if a researcher uses the wrong method, a clear misuse, to analyze a specific set of data, then the results may be incorrect." (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

"When an analyst selects the wrong tool, this is a misuse which usually leads to invalid conclusions. Incorrect use of even a tool as simple as the mean can lead to serious misuses. […] But all statisticians know that more complex tools do not guarantee an analysis free of misuses. Vigilance is required on every statistical level."  (Herbert F Spirer et al, "Misused Statistics" 2nd Ed, 1998)

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