A negative value for correlation indicates what?

Answer 1

Data can be correlated (meaning there is an indication of a relationship) either positively or negatively. The datasets of two variables (x,y) which have a negative correlations, when plotted, will show a negative trend, that means with increasing values of x, there will be, generally, decreasing values of y. An example of negative correlation, would be the more hours someone exercises, the less they weigh, if weight loss is measured as a negative number and weight gain as a positive number. In this case x= hours exercised, y = final weight - original weight. For presentation purposes, we frequently define our variable to show positive correlations. As per the above example, I could have defined y = original weight - final weight, which would show a positive correlation and plot as an upward trend. It would not change the absolute value of correlation just the sign. You may check wikipedia under correlation to get more understanding.