I would like to read and understand more about High Maturity practices and I am also very keen to develop statistical skills so I will be able to construct a PPM. Can you please recommend some good reference books and/or links?
I would recommend the following books:
“Statistical Methods from the Viewpoint of Quality Control” by Walter A. Shewhart
“Understanding Variation: The Key to Managing Chaos” by Donald J. Wheeler
“Measuring the Software Process” by William A. Florac and Anita D. Carleton
“Building Continual Improvement” by Donald J. Wheeler and Sheila R. Poling
“Metrics and Models in Software Quality Engineering” by Stephen H. Kan
“Practical Software Measurement” by John McGarry, David Card, Cheryl Jones, Beth Layman, Elizabeth Clark, Joseph Dean, and Fred Hall
These are all excellent reference books to better your understanding of statistical and quantitative thinking.