Which is strongest value for correlation coefficient -0.75 and 0.25?

The further the correlation coefficient is from 0 (ie the closer to ±1) the stronger the correlation.

Therefore -0.75 is a stronger correlation than 0.25

The strength of the correlation is dependant on the absolute value of the correlation coefficient; the sign of the correlation coefficient gives the "relative" slope of correlation line:

• +ve (0 to +1) means that as one variable increases the other also increases;
• -ve (0 to -1) means that as one variable increases the other decreases.