The drop-down list in the Data field contains the names of all matrices and vectors, other than 1-by-1 matrices (scalars) in the MATLAB workspace. Select the array containing the data you want to fit. The actual data you import must be a vector. If you select a matrix in the Data field, the first column of the matrix is imported by default. To select a different column or row of the matrix, click Select Column or Row. This displays the matrix in the Variable Editor, where you can select a row or column by highlighting it with the mouse.
Alternatively, you can enter any valid MATLAB expression in the Data field.
When you select a vector in the Data field, a histogram of the data appears in the Data preview pane.