This discussion goes to the heart of a subject which we don’t discuss nearly enough and that is interactions.
Interactions and Systems
July 26th, 2008 — Deming, General Management, Statistical Thinking
Hypothesis Testing III - The statistics
July 20th, 2008 — Research Methods, Scientific Thinking, Statistical Thinking
To continue, we need to define a couple of terms. The first is a probability density function and the second is a sampling distribution.A probability density function expresses a particular function in terms of integrals. Thus for a frequency distribution smoothed (over repeated sampling) to form a curve as shown below, the area under the curve can be calculated and the probability of a given value occurring in the distribution can be assessed as a proportion of the amount of the curve that is to the left and/or to the right of the value. In a normal distribution, z values are used to do this.
Hypothesis Testing II - The logic
July 7th, 2008 — General Management, Research Methods, Scientific Thinking, Statistical Thinking
A hypothesis is a supposition made as a basis for research or reasoning without regard for its truth. So says the Oxford dictionary. What starts the hypothesis testing process is just such a supposition. In the justice system example we made, there is a supposition on the part of law enforcement that the apprehended person committed the crime.In pharmaceutical testing, there may be a supposition a given medicine will reduce cholesterol values in blood tests.Because of the nature of induction we can never prove theory going forward. As a prediction we recognize that the samples of interest are not those of the past, but rather those of the future and they have not happened yet. Thus they are not available to be sampled for our study and...
Read more>>
Quality, Productivity and Competitive Position
July 4th, 2008 — Deming, General Management, Statistical Thinking
June marked the 25th anniversary of the publication of Dr. W. E. Deming’s first management book, “On Quality, Productivity and Competitive Position”. Deming lived both in Washington D. C. and New York where he kept an apartment on Hudson St. in the Village. He was a professor at NYU’s Graduate School of Business Administration from 1946 until his death in 1993. He also taught for years at Columbia. While returning to his apartment one evening in 1968 he was mugged and stabbed and was rushed to St. Vincent’s Hospital where he spent several days; a true New Yorker, indeed.Deming was born in 1900 in Iowa and spent the bulk of his early childhood in Polk City and then at around age 7 moved to Cody, Wyoming and later Powell, Wyoming....
Read more>>
Tests of Hypothesis
July 3rd, 2008 — General Management, Research Methods, Scientific Thinking, Statistical Thinking
When discussing hypothesis testing, I have, from time to time, used the example of the criminal justice system to act as a metaphor for the logic and philosophical issues involved. It remains a good way to pose the logical dilemmas and the types of errors involved and to also discuss the idea of a system generally and how to improve it.There is, in the American system of justice, a presumption of innocence. That is, the burden of proof that a crime was committed rests with the government (the prosecutor). In a research situation, the burden of proof rests with the advocate of the research hypothesis (e.g. a researcher may assert that this drug will work to cure this disease)Using our criminal justice example, a first hypothesis (in statistics...
Read more>>
