By |Published On: September 19, 2025 at 8:04 pm PDT|Last Updated: September 19, 2025 at 10:11 pm PDT|

Two Sigmoidal Dose Response Curves

This tutorial will show how to use the TechGraph Editor to fit two sigmoidal curves to two set of XY data points.   A sigmoidal curve is fitted to the mean values in Graph A and Graph C.  Values in Graph B and Graph D are displayed as error bars for Graph A and Graph C.  Shown below are the settings in the Data Table and the Edit Chart used to create this chart.        

Data Table – Sample data can easily be changed or replaced by pasting data from an external worksheet.
  • Graph Type is Scatter.
  • X Data Type is Number.  X Data column contains the X values that are converted to logarithms.
  • Graph A series contains the mean values for the first sigmoidal. Graph C contains the mean values for the second sigmodial.
  • Graph B series contains the error bar (SD) values for Graph A. Graph D contains the error bar values for Graph C.

     Note:   Click on the “Help” button on the toolbar to find out how to edit, delete, copy and paste in the Data Table.

Edit Chart – A set of icons (Titles, Settings, X Axis, Y Axis, Curves and Error Bars) to change the settings and appearance of the chart.      

     Settings  – specify the color, marker type and size for Graph A and Graph C marker.         

  •  Click on the “DarkOrchid triangle” (Graph Style) to show the marker Style for Graph A pop-up.   You can change the Color, Type and Size for Graph A marker.   Click on Apply to save the changes.
  •  Click on the “RoyalBlue circle” (Graph Style) to show the marker Style for Graph C pop-up. You can change the Color, Type and Size for Graph A marker.  Click on Apply to save the changes.

     X Axis      

  • Enter values in Minimum, Maximum and Major Div to set the X Axis scale and divisions.  Leave these values empty for automatic scaling. 
    • The values for this example are Minimum = -10, Maximum = -4 and Major Div = 6.

     Y axis

  • Enter values in Minimum, Maximum and Major Div to set the Y Axis scale and divisions.  Leave these values empty for automatic scaling. 
    • The values for this example are Minimum = -10, Maximum = 110, Major Div = 5, Major Start = 0 and Major End = 100.

     Curves & Error Bars 

  • “Error Bar On” is selected for Graph A and Graph C.
  • Click on “Dose Response (Sigmoidal)” (Curve Fit) for Graph A to show the Curvefit Selection for Graph A pop-up.  For this example, “Dose Response (Sigmoid)” is selected from the Selection list.  Click on Apply to save the changes.  Repeat the same step for Graph C.
  • Click on Curve Style for Graph A to show the Curve Style for Graph A pop-up.  Curve Color (“Black”) is selected for the sigmoidal curve color.  Use the Thickness and Line Type selection list to change the line style. Click on Apply to save the changes.  Repeat the same step for Graph C.

    Edit Chart Toolbar Options

  •  Print Chart prints your chart.
  •  Download Image downloads your chart as an SVG(Scalable Vector Graphics) file or image file(PNG, JPEG, TIF, PDF).
  •  Drawing Objects customize your chart with labels, lines, arrows, circles, images, and logos.
 Getting Started: