
CORRELATE, CORRELATION  ZERO ORDERAny variable which is correlated (the relationship between the two variables is one of correlation) with another variable. Age and sex are the two strongest correlates of crime.
Correlation is a measure of association between two variables. The variables are not designated as dependent variable or independent variable. The value of a correlation coefficient can vary from minus one to plus one. A minus one indicates a perfect negative correlation, while a plus one indicates a perfect positive correlation. A correlation of zero order means there is no relationship between the two variables.
When there is a negative correlation between two variables, as the value of one variable increases, the value of the other variable decreases, and vise versa. In other words, for a negative correlation, the variables work opposite each other. When there is a positive correlation between two variables, as the value of one variable increases, the value of the other variable also increases. The variables move together.
The two most popular correlation coefficients are: Spearman's correlation coefficient rho and Pearson's productmoment correlation coefficient. The standard error of a correlation coefficient is used to determine the confidence intervals around a true correlation of zero. If your correlation coefficient falls outside of this range, then it is significantly different than zero. The standard error can be calculated for interval or ratiotype data (i.e., only for Pearson's productmoment correlation). The significance (probability) of
the correlation coefficient is determined from the tstatistic. The probability of the
tstatistic indicates whether the observed correlation coefficient occurred by chance if
the true correlation is zero. In other words, it asks if the correlation is significantly
different than zero. When the tstatistic is calculated for Spearman's rankdifference
correlation coefficient, there must be at least 30 cases before the tdistribution can be
used to determine the probability. If there are fewer than 30 cases, you must refer to a
special table to find the probability of the correlation coefficient. CORRELATION ZERO ORDER What is the meaning of
correlation of zero order or near zero correlation? It means simply that two
things vary separately. That is, when the magnitudes of one thing are high; the other's
magnitudes are sometimes high, and sometimes low. It is through such uncorrelated
variationsuch independence of thingsthat we can sharply discriminate between
phenomena. "Two variables can have a
causal relation even in the absence of a nonzero correlation. Zeroorder correlations can
be spuriously small as well as spuriously large. This outcome is especially likely in the
complex causal networks that likely underlie realworld phenomena. Hence, the three
conditions for causal inference from correlational data are misspecified. They probably
reduce to two: temporal priority and a nonzero correlation after controlling for all
reasonable third variables." Alan & Bo's Correlation & Causality Blog 
correlationcausality.blogspot.com Zeroorder correlation matrices are used as the starting point in the analysis of causal structure inherent to the data. Theory of correlation  ZeroOrder, Partial and Multiple Correlation Coefficients;. Correlation Ratios; Weighted Correlations. 