The phrase "are four principal components" is correct and usable in written English.
It can be used when discussing or describing a specific number of main elements or factors in a particular context, such as in a scientific or analytical discussion.
Example: "In our analysis, we found that there are four principal components that significantly influence the outcome of the experiment."
Alternatives: "consist of four main components" or "include four key components".
"These 2014 power units are the most complex ever seen in F1; there are six principal components to them and to have the drivers manage that alone, with the current systems we have on the car in terms of of driver information, it's too much," Smedley told BBC Radio 5 Live.
There are three principal components of the Akt pathway: phosphatidylinositol 3-kinase (PI3K), its antagonist PTEN (phosphatase and tensin homologue deleted on chromosome ten), and the serine/threonine kinase Akt, which is expressed as three different isoforms, Akt1, Akt2, and Akt3, which are structurally similar but transcribed from different genes [ 1].
There were two principal components that accounted for 61%% of the variance in non-workplace related scores (Additional file 1: Table S3b).
Principal component analysis (PCA) revealed that these 26 proteins were correlated, and could be represented by four principal components.
Principal Component Analysis (PCA) was run, and four principal components with eigenvalues greater than one were summed to obtain wealth index values [ 39].
With the component analysis the 11 variables could be associated in four principal components with eigenvalues higher than 1 and representing 76.4% of the total variability.
For example, over 90% of the V2R variation in lab-derived strains can be represented by four principal components (eigenvalues <2).
First, a principal component analysis (PCA) is conducted and the first four principal components (PCs) are recorded.
Component extraction was based on eigenvalues >1, and four principal components were extracted that explained 70% of the variance.
PCA was performed in GeneSpring GX 11.0 using four principal components and was mean-centred and scaled.
