# Curve Fitting

• The independent variable is plotted on the abscissa (x-axis) and the dependent variable on the ordinate (y-axis).
• The regression coefficient is a measure of the slope of the line. It ranges from –∞ to +∞. A regression coefficient of zero means the line is horizontal; a positive value corresponds to an upward slope and a negative value to a downward slope. The larger the value the steeper the slope.
• The correlation coefficient is a measure how close the line fits the data. It ranges from –1 to +1. A correlation coefficient of zero means that there is no correlation. The more the value approaches 1, the better the line fits the data. A negative value corresponds to a reverse relation.
• Correlation or association doesn’t necessarily mean causation.
• Interpolation is estimation of a non-measured value within the range that has been measured.
• Extrapolation is estimation of a non-measured value outside the range that has been measured.
• One has to be cautious extrapolating data.