Replicate Data Format


SigmaPlot can compute error bars for replicate data from both columns and rows. The options Column Means or Column Median are used for error bars from columns. Similarly Row Means or Row Median is used for error bars from rows.

Replicate data is frequently arranged rowwise and the two data formats X, Y Replicate and Y Replicate can be used to graph and curve fit rowwise replicates. The number of replicates allowed is only limited by the width of the SigmaPlot worksheet (32,000).

X, Y Replicate

This format is used to graph or curve fit row replicate data. Column 1 of the following worksheet contains X data and columns 2 through 4 contain replicate values. The replicates are arranged rowwise with replicates for x = 1.0 following in columns 2 – 4 of the same row.

Use the X, Y Replicate format to create a scatter plot of this data by selecting the Scatter Plot and Simple Scatter – Error Bars icons. In the Graph Wizard select Row Means as shown below. If you want the symbol to be the median value then select Row Median.

For the Upper and Lower error calculation select Standard Deviation. The list shows the numerous other options available and that the upper and lower error calculations may be different.

Click Next and select the X, Y Replicate format. Then click column 1 for X, column 2 for Start Set 1 and column 4 for End Set 1. Click Finish to create the following graph. Each symbol in the graph is a row mean and the error bars are computed rowwise.

You can curve fit this data by using the “Right Click – Fit Curve” feature. By doing this, the curve fitter recognizes the data format used in the graph (X, Y Replicate) and automatically uses this same format. Place your cursor over one of the four data points above and right click. Then select Fit Curve from the dropdown menu. You are placed in the Regression Wizard. Select the Exponential Decay Equation Category and the Single, 3 Parameter equation. Click Next to see that the data has been selected and the data format is X, Y Replicate.

Click Finish to add the fit line to the graph. The fit was performed using all replicate y values.

Y Replicate

This format assumes that the X values are the integers {1, 2, 3, …}. Otherwise it treats replicates just like the X, Y Replicate format.

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