Negative correlation means that if you graph it, you get a negative slope.

Constant correlation means that if you graph it, you get a horizontal (or vertical) line.

For example, a positive correlation would result if I plotted the daytime high temperature with the number of homes in town that ran their AC that day. The hotter it is, the more people there would be who would turn on the cold air, while lower temperatures would result in fewer ACs running.

A negative correlation would occur if I plotted the daytime high temperature with the number of homes who turned on their heater. The lower the temperature, the more heaters running, while a higher the temperature would result in fewer heaters being turned on.

A constant correlation usually reflects a faulty sample. For example, if I want to compare age and height among children I could measure their heights and ask them their ages. If I plotted the resulting points and found that I had various heights, but all the ages were 10 yrs old, I would have a straight line on the graph. This would also tell me that when I collected the data, I hadn’t asked a variety of kids to let me check their heights — I had only asked 10 year olds.

I hope this helps!

RE:
what does positive correlation,negative correlation, No correlation, and constant correlation mean?
i need help with the meanings

In a positive correlation, as the values of one of the variables increase, the values of the second variable also increase. Likewise, as the value of one of the variables decreases, the value of the other variable also decreases. The example above of income and education is a positive correlation. People with higher incomes also tend to have more years of education. People with fewer years of education tend to have lower income.

Negative correlation

In a negative correlation, as the values of one of the variables increase, the values of the second variable decrease. Likewise, as the value of one of the variables decreases, the value of the other variable increases.