Installing the Data Curve Fit Creator Add-in

The Data Curve Fit Creator Add-in for Microsoft Excel is a specialized tool by SRS1 Software that expands Excel’s native regression capabilities by adding advanced curve-fitting, interpolation, and data smoothing functions directly to the workbook. Key Regression & Fitting Functions

Unlike standard Excel tools that are often limited to basic linear or simple polynomial trends, this add-in provides functions that can be used directly in cells:

Weighted Polynomial Fits: Allows you to apply specific weights to data points, which is useful for reducing the impact of outliers or forcing the curve through a critical point.

RegionFit (Local Regression): Performs local regression (Loess), allowing you to achieve a highly customized fit by adjusting the “window size” and fit order for specific data segments.

Advanced Splines: Introduces several specialized spline types that offer better control than standard cubic splines:

Akima Spline: Produces a tighter, more local fit that avoids the “oscillations” or overshooting often seen with cubic splines in noisy data.

Bessel Spline: Uses internal parabolic fits to remain better behaved than traditional third-order polynomials.

OneWay (Monotonic) Spline: Guarantees the resulting curve only increases or decreases if the source data does, preventing unrealistic dips.

FlexSpline: Grants the user manual control over the slope of the curve at any specific data point. Data Smoothing & Filtering

The add-in includes several filters to clean up noisy datasets before or during the fitting process: Moving Average & Median Filter Gaussian Smoothing Filter Usage & Compatibility

Integration: Functions are used like standard Excel formulas (e.g., polyfit(x_range, y_range, target_x, order)).

Platform: It is available for both Windows and Mac versions of Excel.

Trial: A 30-day fully functional trial is typically available for new users. If you’d like to dive deeper, I can explain: How to set up a weighted fit to handle outliers. The technical differences between Akima and Cubic splines.

How to use the FlexSpline to manually adjust your curve’s slope.