my trendline equation on excel has no y intercept value

This R2 value matches the graphical output Excel provides for the R2 value if I format the plot's trendline to not have a set y-intercept, as seen in the image below. I get a coefficient of determination, R2 = 0.9742, as seen in the image below. := LINEST(known y's, known x's, TRUE, TRUE), where the third argument I used 'TRUE' to, as Excel claims, 'to calculate b normally'.

There is a discrepancy between the two coefficients of determination given by Excel, 0.779 versus 0.9602.įurthermore, if I tell Excel's LINEST function to calculate the regression without a set intercept, e.g. When I use Microsoft Excel's LINEST function I get a coefficient of determination, R2 = 0.9602, as seen in the image below.įor the LINEST function I used: =LINEST(known y's, known x's, FALSE, TRUE), where in the third argument I used 'FALSE' to set the y-intercept, b, equal to zero. Displaying the coefficient of determination on the plot, Excel shows it to be, R2 = 0.779.

I applied the trendline this way because based on Darcy's Law the y-variable (volumetric flow rate) should be zero when the x-variable (pressure gradient) is equal to zero. I plotted the data in Microsoft Excel and applied a linear trendline with a the y-intercept set to zero. Note*: For simplicity here, I rounded my dataset numbers to the nearest whole number. I am plotting my data in a way that compares the data to Darcy's Law, a phenomenological model for fluid flow through porous media that says for certain conditions the volumetric flow rate is proportional to pressure gradient.īelow is my dataset and my plot of the data. My question came about when I was trying to plot experimentally measured fluid flow data. The equation of the line would be y = mx + b and b = 0.

For example, the y-intercept would be set equal to 0 when the x-variable is 0. How can I calculate the coefficient of determination for a linear regression with a defined y-intercept? The y-variable is the dependent variable and the x-variable is the independent variable. So I'll start by asking my question and then explain what has caused me to ask this question.

My trendline equation on excel has no y intercept value