If our data is in digital form, we can use computational techniques to determine if it is exponential or not.

Ratios

Using a computer we can take the ratio of neighboring points in the data. If these ratios are all the same or very similar, the data is behaving exponentially.

In a spreadsheet we usually use the numbers in a single column and two rows. Something like = B3/B2.

Fitting

Alongside our measured data, we can plot an exponential function and adjust the parameters until it is makes a good approximation of our measured data. If it follows it closely, our data is behaving exponentially.

y = A e^{bx}

We adjust A and b until it fits the data.

In a spreadsheet, we would place A and b in a cell, create a column of data with our function, plot both, and adjust A and b.

Logarithmic Scales

Spreadsheet programs have the ability to plot either the x-axis, the y-axis, or both axes using a logarithmic scale. If you plot your data with a linear y-axis and a logarithmic x-axis, your data will lie along a straight line.