A Zest of Non Parametric Testing -The Chi Square
Test
In our
hypotheses testing examples, we used means and variances to
determine if there were statistically significant differences
between samples. What happens if the data we want to compare
cannot be reduced to means and variances? What if the data are
nominal or ordinal?
Suppose that a
molding machine has historically produced metal bars with
varying strength (measured in PSI) and the strengths of the bars
are categorized in the following table. The ideal strength is
1998 PSI.
Building a Multiple
Regression Model Using Minitab and Excel
In the
Simple
Linear Regression model that we built to determine the effect of
the variation of the price of gas on the quantities sold, we only
used one independent variable, the price per gallon. In the case of
our example, the variations of the quantities sold could have been
explained by other factors such as new people moving in or out of
the city, the building of a new freeway, the building of a new
factory...etc. All these independent variables can have a
significant impact on the variation of
y and need to be taken into account for a more accurate regression
model. |
Analysis Of Variance (ANOVA) in short
plain English!
The purpose of this article is to present the Analysis Of Variance
under less confusing auspices, in plain English.
It is obvious that since most computers are equipped with some form
of spreadsheet, specially Excel, using the embedded Data Analysis
tool would make it painless to obtain the information we are
seeking. But since the Statistics software tools do not provide any
interpretation of the results, nor do they explain the process that
leads to the results, understanding the step by step process of
ANOVA becomes paramount. |
