Automate a routine analysis, example of Principal Component Analysis, in XLSTAT

Dataset for automating a routine analysis

Two Excel workbooks with both the data and the results can be downloaded by clicking here. The data used is the process measurements of food samples.

Creating the VBA codes to be reused

We are going to create a Principal component analysis template on one dataset and use it on the second.

Generating the code to automate a routine analysis

Open the first file Automation_1.xls

Once XLSTAT-Pro is activated, go to the menu Options and in the tab Advanced enable the option Show the advanced buttons in the dialog boxes.

Principal Component Analysis

The next step of the automation procedure is to set up your statistical analysis.

Select the XLSTAT / Analyzing data / Principal components analysis command, or click on the corresponding button of the Analyzing Data toolbar (see below).

automate a Principal Component Analysis

Principal Component Analysis software

In the General tab, set the following:

Observations/variables table: Columns B to G
Data format: Observations/variables table
PCA type: Pearson (n)
Variable labels: enabled
Observation labels: ticked and select the column A for the sample name
Sheet: chosen to display the results in a new sheet

automation software

Go to the next tab Options. For the option Filter factors, choose Maximum number and set the value to six. This way all the components will be calculated.

automate an analysis in Excel

Go to the tab Outputs. Here we want to get a synthetic report so we will only select the following:

* Eigenvalues,
* Factor Loadings,
* Variables/Factors correlations,
* Factor scores.

Principal Component Analysis package

Finally we are going to use all three plots that can be selected in the Charts tab:

* Correlation charts
* Observations charts
* Biplots

Principal Component Analysis tools

Now we have specified all the setting we will save the code to be reused.

Generate the VBA code to be reused

Click on the grey button at the bottom left of the dialog box: Click this button to generate the VBA code that will allow you to run the dialog box from your code.

Principal Component Analysis with MS Excel

Once you have pressed the button a Notepad document will appear containing the VBA code. Save the code under a name that is easy for you to remember, for example in this case we use "VBA-PCA-recipe1".

VBA code in XLSTAT

Results of the analysis

Click on OK to launch the analysis.

Now choose the plot for the axes F1 and F2 by clicking Select, then change the selection to Abscissa F3 and Ordinates F4. Once you have completed this click again on Select and then press Done.

automation tutorial

Have a look at the biplot.

Principal Component Analysis software Excel

This process is usually stable so we can expect little variation. You can see that all the samples are centered tidily around the middle of the center of the plot.

Reusing the VBA code

Now open the second file Automation_2.xls

Press Alt+F11 together in order to launch the Visual Basic Application. Then select Sheet1 in the folderVBAProject(Automation_2.xls) and finally right click and opt for the action Insert / Module

automate a routine analysis

The next step is to copy and paste the code contained in the Notepad file into this module.

automation

Note that the LoadRunPCA call has a number of parameters, corresponding to the different controls on the dialog box, as well as a final parameter "SettingsFile:=", which is followed by a file name. This file contains the most recently used options are saved. When you use this VBA code you will usually want to remove "SettingsFile:=" and the following filenamer, as the saved settings in the file will override the ones specified in the function call. Alternatively, you may include just the "SettingsFile:=" parameter, and remove the other parameters, to always base the analysis on the settings in that file.

At this step you can add more codes to enable the programme to perform other actions.

Go to the menu Run / Run Macro located in the menu bar.

automation of analysis

Then you need to run first the macro called "RunMeOnce". This will make a link between the file and the XLSTAT project where the code is stored. Select it in the list and click on Run.

VBA automation software

When this has been completed, run the second macro called "MySub". Return to the menu Run / Run Macro and this time select the macro "MySub" before pressing the button Run.

This will in turn execute the code in question and you now have a sheet "PCA" containing the results.

Now if we look at the biplot of the second analysis we notice that this time one of the samples seems to be further away that the other samples. Sample 13 may be an outlier.

Principal Component Analysis biplot

Have a look at this video to have a demonstration on how to automate data analysis with XLSTAT software.

Click here for other tutorials.

About KCS

Kovach Computing Services (KCS) was founded in 1993 by Dr. Warren Kovach. The company specializes in the development and marketing of inexpensive and easy-to-use statistical software for scientists, as well as in data analysis consulting.

Mailing list Join our mailing list

Home | Order | MVSP | Oriana | XLStat
QDA Miner | Accent Composer | Stats Books
Stats Links | Anglesey

Share: FacebookFacebook TwitterTwitter RedditReddit
Del.icio.usDel.icio.us Stumble UponStumble Upon

 

Like us on Facebook

Get in Touch

  • Email:
    sales@kovcomp.com
  • Address:
    85 Nant y Felin
    Pentraeth, Isle of Anglesey
    LL75 8UY
    United Kingdom
  • Phone:
    (UK): 01248-450414
    (Intl.): +44-1248-450414