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15 Data Analysis

Introduction

Origin contains powerful tools for all of your analytic needs, including peak analysis, curve fitting, statistics, and signal processing. The output of one operation can be used as input for another, allowing for a chain of operations and their associated results to be updated. You can easily update results when input data or analysis parameters are changed and avoid the trouble of repeating the procedure from the beginning.

The following sections cover (1) delineating the data that you wish to analyze and (2) the Origin and OriginPro tools available for analyzing that data. Please refer to the How to Handle Repetitive Tasks chapter of this User Guide for more information on Analysis Templates, Dialog Themes and other time-saving features.

Origin 2016 introduced add-on tools called Apps. Since being introduced, many new exploratory and analysis-related tools have been added to OriginLab's File Exchange and more tools are being released all the time. Please visit the File Exchange to review available tools.

Selecting Data

Origin's analysis can be performance from workbook or graph windows. By default analysis will be on done on highlighted data in worksheet or active plot in graph. You may want to restrict your analysis to a subset of the data; say, a certain range of rows or columns in a worksheet, or a certain X range in a graph.

You can either do the data selection (with methods mentioned below) before opening an analysis dialog or after opening the dialog. Most of Origin's X-Function based analysis tools have a Input Data branch with standard range selection control that you'll want to become familiar with (we explain the control, below).

Selecting Data in the Worksheet

When you highlight a range of worksheet data, then open one of X-Function based dialog boxes -- that would include nearly all of those that open from the Analysis or Statistics menus -- you will see your range selection already entered into the dialog box Input Data branch. Most will find that selecting worksheet data prior to opening an Analysis or Statistics dialog box, is the easiest way to specify which data you wish to analyze.

Selecting Data in the Worksheet-1.png

If you open one of the X-Function dialog boxes without pre-selecting your data, the first thing you should do after openning a dialog is to select data in Input Data branch:

XF range selection control.png
  1. Click the range selection control next to Input Data. The dialog box will roll up.
  2. Go to worksheet and highlight your worksheet data, then click the Xf open dialog.png button at the right end of the rolled up dialog box. The Input Data branch will now show the selected range.

Note that you do not have to select entire datasets (columns). You can select a portion of your worksheet data and analyses will be confined to that selected subset of your data. Also if the analysis supports multiple datasets, you could support multiple ranges such as multiple Y columns or Y ranges. If the analysis only supports one dataset, though you could select multiple ranges, only the 1st range will be picked in analysis.

Selecting Data in the Worksheet-2.png



Note:

  • The Input Data branch has a hierarchical structure. If the analysis supports multiple datasets, you can add multiple ranges under Input Data and they will show as Range 1, Range 2, etc., each with its corresponding X, Y, Error and Row controls.
  • Mousing over each level will show a tooltip of where the data on that level is from (i.e. book, sheet and column).
  • Rows control under each range node lets you set range by row index or X value. If you want to apply the same row range to all ranges under Input Data, click the arrow button to the right of the range node and choose Apply Row Range to All.
  • Depending on where you are in the Input Data hierarchy, range selection button may have some limitations. E.g. if you click range selection control next to Y, though you could select multiple columns in a worksheet, only the 1st column is accepted.
  • Click the arrow button to the right of the range selection control will show more selection options, such as pick a column there to do quick data selection.
  • Depending on which level you are in, the selection options when clicking the arrow button may vary, such as clicking the "arrow" button next to Input Data, you will see a Select Columns... menu, which opens Column Browser to select multiple columns even from different worksheets.

XF shortcut menu.png

Use List Datasets drop-down list to filter which sheets you want to pick from. The top panel list can be sorted by clicking any of the column headings, making it easy to select, for example, all columns that share the same LName or Comments. Then click Add button to add the column to your selection list in bottom panel. To modify the data input range of any dataset, click the range button to the right of any dataset added to the bottom panel and edit the From and To values.

Selecting Data in the Graph

When a graph window is active and you select one of the Analysis menu tools, the default behavior is for the analysis dialog box to open showing the selected range of the active dataset as your Input Data (note that analysis dialogs include an Input Data node that allows adjustments -- adding more datasets with the interactive range selector button, changing a data range, etc.).

The active dataset is the one that shows in the data list (bottom of the Data menu) with a check mark next to it. Note that this analysis dialog box behavior applies even to plot groups. You can force an Analysis dialog box to register a particular data range by clicking on another of the data plots listed at the bottom of the Data menu.

Select Data from Graphs-1.png

Alternately, you can graphically set the range for your analysis by selecting one or more plots in the graph window:

  • If your data plots are not part of a plot group, you can click once on the intended plot before opening an Analysis dialog box and this will set the Input Data range to the selected plot.
  • If your data plots are part of a plot group, click once on any of the plots in the group to set Input Range to all plots in the group; or click a second time on any plot to restrict analysis to the selected plot (note that this does not switch the active dataset). Alternately, you can pre-select multiple plots using the Regional Data Selector (see below).

You can indicate the active dataset by placing a red rectangle around the plot's legend entry. To turn this feature on, click on your graph window, select Format: Page Properties..., click on the Legends/Titles tab and choose Indicate Active Dataset.

Selecting a Subset of Your Data Graphically

You can graphically select a range of data using the Regional Data Selector tool:

  1. With a graph window active, click and hold the Regional Data Selector button Quick Help Reg Data Sel button.png on the Tools toolbar, and then choose Selection on Active Plot or Selection on All Plots.
  2. Drag out a rectangle or freehand object to select an area of the plot(s). Press Space to toggle between rectangle Select Data from Graphs-3.png and freehand modes Select Data from Graphs-4.png.
Select Data from Graphs-2.png

When you make your selection, data markers appear on the graph, delineating the selected range(s). You can work with graphically selected data using Origin's analysis tools (e.g., Linear Fit), but note that some analysis dialog boxes do not work on multiple data ranges. The smoothing dialog box, for example, (Analysis: Signal Processing: Smooth...) will only smooth data in the active dataset or a single, selected plot.

Tutorial: Linear Regression on Partial X Range

  1. Import the file \Samples\Curve Fitting\Exponential Decay.dat into a new workbook.
  2. Select all Y columns and create a line plot.
  3. Click and hold the Regional Data Selector button on the Tools toolbar, and then choose the Selection on All Plots button Quick Help Reg Data Sel All button1.png.
  4. Drag out a rectangle to select the tail-end of the three curves between values of approximately 0.6 and 1.0 along the X axis.
  5. Use the Analysis:Fitting:Linear Fit menu to open the Linear Fit dialog.
  6. Input Data branch is filled with three ranges. Mouse over Input Data branch will show tooltip which shows 1X,1Y, ...3X and 3Y.
  7. If you want to change the data selection, click the arrow button in Input Data and choose Reselect All Data from Graph. The dialog will roll up. Drag out a rectangle in graph again to make your selection and then click the Xf open dialog.png button at the right end of the rolled up dialog box. The new data selection will show in Input Data branch.
  8. Accept default Linear Fit settings and press OK to close the dialog. Linear fitting will be performed on all three curves over the selected range.


Data Selection and Fitting.png

  • In addition to the data selection and masking methods discussed in this section, Origin includes data filtering and data reduction tools. Please visit the linked pages for details.

Editing a Data Marker

To edit a data marker:

  • To modify a data range, right click a data marker and choose Edit or double-click on data marker. The red marker changes to dark color with arrows on both ends and cursor changes into a target. Drag start or end marker to a new position or use one of the keyboard shortcuts listed below and modify the data range. To escape edit mode, double-click on the marker or press Enter key.
  • There are other options when right click data marker such as delete marker, delete data, etc..
Select Data from Graphs-7.png

Note: If you have used the Regional Data Selector tool to place markers on multiple plots (Selection on All Plots), be aware that moving markers will affect the data range of the active plot only; the ranges of other selected plots will not follow that of the active plot. This is a limitation of the Regional Data Selector.


Alternately, you can use these keyboard shortcuts to select and edit data markers:

  1. Select data markers using these keys ...
    Hot Key Action
    s Select the first pair of data markers on the graph (those marked with "1").
    Tab Select the next pair of data markers (not in edit mode) or the other data marker of the pair (in marker edit mode).
    Home Return to the first data marker.
    End Go to the last data marker.
  2. ... then activate and edit the data marker using these key combinations:
    Hot Key Action
    Enter Activate the selected data marker for editing. (Press Enter again to exit data selection mode.)
    Arrow Move the active data marker exactly one data point.
    Ctrl/Shift + Arrow Move the active data marker multiple data points.
    Delete Delete the the active data marker.

Difference between Data Markers and Analysis Markers

  • Data Markers define a sub-range that you select using the Data Selector tool.
    If you want to remove the data markers from a graph, you can select Data: Clear Data Markers from the main menu, or click the Clear Data Markers Clear data markers.png button on the Markers and Locks toolbar.
Select Data from Graphs-5.png
  • When the analysis routine is completed, Data Markers are replaced with Analysis Markers. By default, Analysis Markers will not show if the analysis is done on the entire dataset. If performed on a subrange, Analysis Markers will show at the beginning and end of that subrange. To modify the data range and rerun your analysis, you must right-click an analysis marker and choose Change Parameters.... Change the Input Data range and rerun the analysis.
Select Data from Graphs-6.png

Note:
  1. If you set Recalculate to None in the analysis dialog box, then no analysis markers are generated.
  2. Data markers and analysis markers are not exported when you choose File: Export Graphs.
  3. To select the exact same range again for another analysis, click the green lock and choose Plot Input Data with Data Markers to create a new graph and do analysis on it.
  4. There is a Markers and Locks toolbar to control analysis markers and locks, such as Marker Hide Show Marker hide show.png to toggle analysis markers on or off, etc. There is also Data: Analysis Marker menu and context menus when right click on analysis marker, green lock, in graph layer to control analysis markers.

Data Masking

Masking is another tool that you can use when you want to analyze only a subset of your data, or when you have spurious data points that you do not want included in your analysis. Mask or unmask will trigger recalculation.

You can mask data points in either your worksheet or your graph. When data exist in both the worksheet and the graph, masking data in one will mask the corresponding data in the other.

Note that there are two toolbars with masking buttons: the Tools toolbar and the Mask toolbar. The masking tools on the Tools toolbar work only with graphs. The tools on the Mask toolbar work with worksheets or graphs.

Masking Data in Worksheets

Masking of worksheet data excludes masked data from analysis operations. When plotted, masked data points display in the mask color.

Action Toolbar Button Shortcut Command Notes
Mask data Button Mask Range.png Mask: Apply Mask the selected data range. Masked data will display in the mask color.
Unmask data Button Unmask Range.png Mask: Remove Unmask the selected data range. Unmasked points are included in analysis operations and plot "normally".
Change mask color Button Change Mask Color.png Mask: Change Color Change the mask color of the masked data range.
Disable masking Button Disable Or Enables Masking.png Mask: Disable Masking Toggle the mask on or off for all masked data in the worksheet.

Masking Data in Graphs

With your graph window active:

  1. Choose Data: Mask Data Points from the main menu or click the Mask Points on Active Plot button or Mask Points on All Plots button on the Tools toolbar. This activates the Regional Mask Tool.
  2. To mask a single point, double click on the point.
  3. To mask a region of points, similar to Regional Data Selector, press the space bar to toggle among masking by row index, rectangular region or by freehand region. then draw a rectangle or freehand region to mask data in that region.

Note that the cursor changes as you:

  • Press space bar to toggle masking data points by row index number, rectangular region or freehand region.
  • Choose the Mask Points on the Active Plot Button Mask On Active Plot.png tool vs. the Mask Points on All Plots of Active Layer Button Mask On All Plots.png tool (Tools toolbar).
Mask Points on Active Plot Mask Points on All Plots of Active Layer Purpose
Masking Data in Graphs-6.png Masking Data in Graphs-7.png Mask data points by row index number. All data points between the lowest and highest selected index numbers are masked regardless of whether they lie inside your rectangle.
Masking Data in Graphs-3.png Masking Data in Graphs-8.png Mask data points by rectangular region. Only the data points inside the rectangle that you drag out, will be masked.
Masking Data in Graphs-4.png Masking Data in Graphs-9.png Mask data points by freehand region. Only the data points inside the region that you drag out, will be masked.

To remove the mask from data points in the graph window:

  1. Choose either the Unmask Points on the Active Plot Button Unmask On Active Plot.png tool or the Unmask Points on All Plots of Active Layer Button Unmask On All Plots.png tool on the Tools toolbar.
  2. Use the space bar, as needed, to choose points by index, rectangular region or by freehand region, then drag to unmask your data points.

There are some useful buttons on Mask toolbar such as

  • Change mask color button to avoid using same color as data plot as mask color.
  • Hide/Show masked points to hide masked points on the screen, printout and exported graph.
  • Disable/Enable Masking Button Disable Or Enables Masking.png button to quickly toggle the mask on or off without removing the masked points.

Drawing or Moving, or Deleting Data Points in the Graph

This collection of tools and menu-driven operations is helpful in exploring certain "what if" scenarios, or to quickly generate some data for purposes such as testing a fitting function. These procedures work only with 2D scatter plots.

  1. Activate the graph window.
  2. Click on the Draw Data Tool Button Draw Data.png.
  3. Make sure that the correct graph layer is active and place the cursor on the graph.
  4. Double-click to create data points. The Data Display tool opens (if not already open) and displays the X and Y values for each created data point.
  5. When you have finished adding data points, click on another tool (on the Tools toolbar) to exit drawing mode.

When you use the Draw Data tool, you simultaneously create a hidden worksheet named Drawn (worksheets are automatically enumerated, with n = 1, 2, 3, 4, etc.).

Opening the hidden Drawn Worksheet

Right-click on the data plot and select Go to Drawn from the shortcut menu or in Plot Details dialog, with data plot selected on left panel, click the Workbook button.

A Drawn workbook will appear with A(X) and B(Y) columns with coordinate values of your drawn data plot.

Deleting a Data Point

You can delete individual data points from your graph:

  1. Select Data: Remove Bad Data Points.
  2. Double-click on the data point, or click to select the data point and press ENTER key.
  3. Click Arrow button on Tools toolbar or press ESC key to exit the Remove Bad Data Points mode.

The data point is deleted from both the data plot and the worksheet cell. In the worksheet, only the data cell for the Y value will be cleared and shown as missing value.

Moving a Data Point

You can move individual data points in the graph. Understand that when you do this, you are changing the plot and the underlying data:

  1. Select Data: Move Data Points (you'll be warned that you are about to change your data).
  2. Click on the point you want to move (change X and Y coordinates). Place crosshairs on the point and drag; or use the arrow keys.
  3. Click the Pointer button Button Pointer.png on the Tools toolbar or press ESC to exit the Move Data Points mode.

The data point is moved in the plot and the X and Y coordinates are changed in the worksheet cell.

Mathematics

Origin provides a number of mathematics tools to perform basic calculations, interpolation, and area or volume calculations.

Basic Math

Tool Name Description Menu Entry
  • Simple Column Math/Simple Curve Math
  • Normalize Columns/Curves
  • Average Multiple Curves
  • Differentiate
  • Perform basic calculations on worksheet columns or XY data plots
Analysis:Mathematics (workbook, graph)
  • Differentiate Gadget
  • Perform differentiation over a region of interest in a graph
Gadgets:Differentiate... (graph)
  • Set Column Values
  • Use formulae to set/transform worksheet column values
Analysis:Mathematics (workbook)
  • Inverse
  • Generate pseudo inverse of a matrix
Analysis:Mathematics (matrix)
  • Median Filter
  • Special Filter
  • Custom Filter
  • Apply median/special/custom filter to a matrix
Analysis:Mathematics (matrix)

Interpolation

Tool Name Description Menu Entry
  • Interpolate Gadget
  • Perform interpolation over a region of interest
Gadgets:Interpolate... (graph)
  • Interpolate/Extrapolate
  • XYZ Trace Interpolation(3D Graph)
  • Trace Interpolation(2D Graph)
  • Perform interpolation/extrapolation on a group of XY data.
  • Perform periodic interpolation on XYZ worksheet data
  • Perform interpolation on cycle or periodic curves
Analysis:Mathematics (workbook, graph)
  • Interpolate/Extrapolate Y from X
  • 3D Interpolation
  • Perform interpolation/extrapolation on a group of XY data to find Y at given X values.
  • Perform interpolation with a 3D function on XYZ dataset.
Analysis:Mathematics (workbook)
  • 2D Interpolate/Extrapolate
  • Perform 2D interpolation/extrapolation for a matrix
Analysis:Mathematics (matrix, graph from matrix)

Area/Volume Calculation

Tool Name Description Menu Entry
  • Integrate Gadget
  • Perform integration over a region of interest in a 2D Graph
Gadgets:Integrate... (graph)
  • Integrate(2D Graph)
  • Polygon Area(2D Graph)
  • XYZ Surface Area (3D Graph) (Pro Only)
  • Perform integration on input data
  • Calculate the area of enclosed plot regions
  • Calculate the area of the XYZ surface
Analysis:Mathematics (workbook, graph)
  • 2D Volume Integrate (Pro Only)
  • Matrix Surface Area (Pro Only)
  • Calculate the volume beneath the matrix surface from zero plane
  • Calculate the area of the matrix surface
Analysis:Mathematics (matrix, 3D graph from matrix)

Curve Fitting

Linear and Polynomial Fit

Linear and polynomial fitting can be performed on worksheet data or data plots in a graph. The menu entries of these tools are listed in the table below. All are available for both workbook or plotted data.

Tool Name Menu Entry
  • Linear Fit
Analysis:Fitting:Linear Fit
or
Gadgets:Quick Fit (graph)
  • Fit Linear with X Error (Pro Only)
Analysis:Fitting:Fit Linear with X Error
  • Multiple Linear Regression
Analysis:Fitting:Multiple Linear Regression
  • Polynomial Regression
Analysis:Fitting:Polynomial Fit
or
Gadgets:Quick Fit (graph)

Nonlinear Curve Fit

You can perform nonlinear curve fitting using one of many built-in fitting functions, or you can create a user-defined fitting function. OriginPro supports implicit function fitting, surface fitting, and fit comparison. Some tools are available only in OriginPro.

The table below summarizes available nonlinear curve fitting tools:

Tool Name Features Menu Entry
  • Quick Fit Gadget
  • Fit a region of interest in a graph interactively
  • Fit with built-in or user-defined fitting functions
  • Fit one or multiple datasets
Gadgets:Quick Fit (graph)
or
Gadgets:Quick Sigmoidal Fit (graph)
  • Nonlinear Curve Fitting
  • Fit with built-in or user-defined fitting functions
  • Fit one or multiple datasets
  • Compare fit, multiple parameter sets
  • Global fit with parameter sharing
  • Global fit, parameter sharing with multiple functions (Pro Only)
  • Fit with replicas
  • Advanced options including bounds, constraints, fit control
Analysis:Fitting:Nonlinear Curve Fit (workbook, graph)
  • Implicit Curve Fitting (Pro Only)
  • Fit with implicit functions
  • Orthogonal Distance Regression (ODR) algorithm
Analysis:Fitting:Nonlinear Implicit Curve Fit (workbook, graph)
  • Surface Fit (Pro Only)
  • Fit data from a matrix or worksheet XYZ columns
Analysis:Fitting:Nonlinear Surface Fit (workbook, graph)
or
Analysis:Nonlinear Matrix Fit (matrix)
  • Fitting Function Builder
  • Create or edit user-defined fitting functions
Tools:Fitting Function Builder
  • Fitting Function Organizer
  • Manage fitting functions by categories
  • Move or share functions between categories
Tools:Fitting Function Organizer
  • Simulate
  • Simulate a curve from a given function
  • Simulate a surface from a given function (Pro Only)
Analysis:Fitting:Simulate Curve
or
Analysis:Fitting:Simulate Surface
  • Fit Comparison (Pro Only)
  • Compare fit results from two datasets using one function function
  • Compare fitting results for one dataset using two fitting functions
Analysis:Fitting:Compare Datasets
or
Analysis:Fitting:Compare Models (workbook, graph)
  • Fit and Rank Functions (Pro Only)
  • Compare fit results of two or more functions for a single dataset
Analysis:Fitting:Rank Models (workbook, graph)

Peak Analysis

Origin provides several tools for peak analysis. With these tools, you can define and subtract baselines, find peaks, integrate peaks, and fit peaks. Some tools are available only in OriginPro.

The table below summarizes various tools available for peak analysis:

Tool Name Features Menu Entry
  • Quick Peaks Gadget
  • Perform peak analysis over a region of interest
  • Create baseline
  • Subtract baseline
  • Find peaks
  • Integrate peaks
  • Fit peaks
Gadget:Quick Peaks (graph)
  • Multiple Peak Fit
  • Pick multiple peaks
  • Fit peaks
Analysis:Peaks and Baseline:Multiple Peak Fit
(graph, workbook)
  • Peak Analyzer
  • Create baseline
  • Subtract baseline
  • Find peaks
  • Integrate peaks
  • Fit multi-peak datasets (Pro Only)
  • Fit baseline (Pro Only)
  • Find hidden peaks
  • Compute many peak characteristics (Pro Only)
Analysis:Peaks and Baseline:Peak Analyzer
(graph, workbook)
  • Batch Peak Analysis
  • Use a theme file created using Peak Analyzer tool
  • Perform batch peak analysis on multiple datasets
Analysis:Peaks and Baseline:Batch Peak Analysis Using Theme
(graph, workbook)

Signal Processing

Origin provides signal processing tools for many tasks, including producing signal transforms, smoothing/filtering, and correlation on 1D and 2D signals. Advanced tools are available in OriginPro.

You may refer to the tables below for the signal processing tools and their menu entry.

Signal Transforms

Tools Menu Entry
  • FFT Gadget
Gadgets:FFT... (graph)
  • Fast Fourier Transform (FFT)
  • Inverse Fast Fourier Transform (IFFT)
Analysis:Signal Processing:FFT (workbook)
  • 2D FFT (Pro Only)
  • 2D IFFT (Pro Only)
Analysis:Signal Processing:FFT (matrix)
  • Short-time Fourier Transform (STFT) (Pro Only)
Analysis:Signal Processing:STFT (workbook)
  • Hilbert Transform (Pro Only)
Analysis:Signal Processing:Hilbert Transform (workbook)
  • Image Profiling
Plot:Image:Image Profiles (matrix)
or
Plot:Contour:Contour Profiles (worksheet, XYZ data)

Filtering

Tools Menu Entry
  • FFT Filter
Analysis:Signal Processing:FFT Filters (workbook)
  • 2D FFT Filter (Pro Only)
Analysis:Signal Processing:2D FFT Filters (matrix)
  • IIR Filter Design (Pro Only)
Analysis:Signal Processing:IIR Filter (workbook)

Smoothing

Tools Menu Entry
  • Smooth
Analysis:Signal Processing:Smooth (workbook, matrix)

Correlation

Tools Menu Entry
  • Correlation
Analysis:Signal Processing:Correlation (workbook)
  • 2D Correlation (Pro Only)
Analysis:Signal Processing:2D Correlation (matrix)

Convolution

Tools Menu Entry
  • Convolution
Analysis:Signal Processing:Convolution (workbook)

Wavelet Analysis (Pro Only)

Tools Menu Entry
  • Continuous Wavelet Transform
  • Discrete Wavelet Transform (Decomposition)
  • Inverse Discrete Wavelet Transform (Reconstruction)
  • Multi-Scale Wavelet Decomposition
  • Smoothing
  • Noise Removal
Analysis:Signal Processing:Wavelet Analysis (workbook)
  • 2D Wavelet Decomposition
  • 2D Wavelet Reconstruction
Analysis:Signal Processing:Wavelet Analysis (matrix)

Other Advanced Tools (Pro Only)

Tools Menu Entry
  • Rise Time Gadget
Gadget:Rise Time (graph)
  • Decimation
Analysis:Signal Processing:Decimation (workbook)
  • Coherence
Analysis:Signal Processing:Coherence (workbook)
  • Envelope Curves
Analysis:Signal Processing:Envelope (workbook)

Image Processing

Origin provides a collection of tools for basic image processing. These tools are accessible from the Image menu when a matrix book is active. The tools are organized in the following sub-menus:

  • Image:Adjustments
  • Image:Arithmetic Transforms
  • Image:Conversion
  • Image:Geometric Transforms
  • Image:Spatial Filters

Topics for Further Reading

 

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