These factors are considered malleable. Indicators are descriptive, and should provide information about the unit of interest (e.g. the system) in terms of central tendency (e.g. mean or median), the precision of the estimate (e.g. the standard error) and the variability (e.g. the standard deviation) of the value of the indicator within the unit of interest. However, descriptive information about ECEC systems, pedagogical and professional practices, and learning and well-being environments becomes even more useful when data from one system can be compared with data from other systems, or over time.