how many sectors are missing in a oecd panel are comparisons valid across different sectors oecd how many observations are missing from a panel are comparisons across different sample valid are statistics of sectors compared is a comparison valid across sectors are statistics comparisons valid across samples? oecd what is the problem with missing data are comparisons across sectors valid are comparisons valid across different sample if data are missing, is a comparison of sector equations valid? are comparisons across different samples still valid are comparisons across sectors statistically valid? can the OECD compare the data across sectors missing observations in panel analysis why is comparisons between sectors valid can a comparison of data across different countries be valid is a comparison between sectors valid are comparisons valid is a comparative analysis valid