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SENSORY DISCRIMINATION TESTS
WHAT ARE SENSORY DISCRIMINATION TESTS? When introducing a new product, discrimination testing is very important in sensory analysis. Sensory discrimination tests allow you to check if a product is significantly different from a second product. They include the triangle test, the duo-trio test, 2-AFC, and more! SENSORY DISCRIMINATION TESTS IN XLSTAT XLSTAT includes the most common discrimination test...
Mandel’s h and k statistics for outliers
What are Mandel's h and k statistics? The Mandel’s h and k statistics (1985, 1991) have been developed to help to identify outliers during inter-laboratories studies. The idea of these statistics is to detect differences between samples obtained from different laboratories to see if a sample contains outliers in comparison to others. The h statistic detects difference between means and the k statistic...
Analysis of a mixture design
What is mixture design analysis Description of models The analysis of a mixture design is based on the same principle as linear regression. The major difference comes from the model that is used. Several models are available. By default, XLSTAT associates a reduced model (Simplified Canonical Model) to centroïd simplexes. However, it is possible to change the model if the number of degrees of freedom...
Coding
Why do we recode data All data cannot be directly used as input data into an analysis. For example, you may need to transform levels into numbers. Also when plotting a chart you may want to change the labels with a code that is shorter or more precise. Doing these tasks manually may be time consuming. This is why we have developed a coding tool that can do the work for you, saving you time and hassle....
Gage Repeatability and Reproducibility for Attributes
What is Gage Gage Repeatability and Reproducibility for Attributes Measurement System Analysis (MSA) or Gage R & R (Gage Repeatability and Reproducibility) is a method to control and judge a measurement process. It is useful to determine which sources are responsible for the variation of the measurement data. Variability can be caused by the measurement system, the operator or the parts. The word...
Screening designs
What are screening designs The family of screening designs aims for the study of the effect of two or more factors. In general factorial designs are the most efficient for this type of study. But the number of necessary tests is often too large when using factorial designs. There are other possible types of designs in order to take into account the limited number of experiments that can be carried...
Partitioning Around Medoids
The PAM algorithm searches for k representative objects in a data set (k medoids) and then assigns each object to the closest medoid in order to create clusters. Its aim is to minimize the sum of dissimilarities between the objects in a cluster and the center of the same cluster (medoid). It is known to be a robust version of k-means as it is considered to be less sensitive to outliers. The Partitioning...
Price Sensitivity Meter (Van Westendorp)
What is Price Sensitivity Meter? This version of price sensitivity analysis (and its impact on sales volume and revenue) is due to Van Westendorp and was presented at the ESOMAR Congress in 1976. It was later enriched by Newton et al. in 1993, to respond to mainstream criticism that this previous method did not take purchase intention into account. This method consists of conducting a survey on a...
ROC curves
The ROC curve generated by XLSTAT allows to represent the evolution of the proportion of true positive cases (also called sensitivity) as a function of the proportion of false positives cases (corresponding to 1 minus specificity), and to evaluate a binary classifier such as a test to diagnose a disease, or to control the presence of defects on a manufactured product. What is a ROC curve? The ROC...
Statistical Power to compare variances
Statistical Power analysis for the comparison of variances in XLSTAT XLSTAT includes several tests to compare variances such as the test of comparison of the variances of two samples. XLSTAT can calculate the power or the number of observations required for a test based on Fisher's F distribution to compare variances. When testing a hypothesis using a statistical test, there are several decisions...