The phrase "a second key observation" is correct and usable in written English.
It can be used when introducing an important point or finding that follows a previous observation in a discussion or analysis.
Example: "In addition to the first observation, a second key observation is that the data shows a significant increase in user engagement."
Alternatives: "another important point" or "a further significant finding."
A second key observation is that cell damage during centrifugation is determined by the combined effects of the extent of compaction achieved and the method of resuspension used.
A second key observation that has emerged from all studies applying these new diagnostics (Brennan et al, 1995; Partridge et al, 2000, 2005; van Houten et al, 2002, 2004; Huang et al, 2007) is that multiple tumour-positive margins are associated with local recurrence, indicating that local spread is more widespread than envisaged earlier.
The second key observation induces to the financial openness in perspectives of both de jure and de facto measures by considering Chinn and Ito (2008) index of the degree of capital openness as a de jure measure.
The second key observation of our study is that exon splicing is more significant and relevant than differential gene expression in SALS signals are more clearly identified and their biological enrichment more robustly defined by profiling aberrant exon splicing than differential gene expression.
The first key observation from these data is the value of the time constant (~600 fs) at the lowest fluences.
The third key observation of our study is the specific identification in SALS of perturbation of cell adhesion and ECM biology, especially cell matrix as opposed to cell cell adhesion genes.
The first key observation is that genomic abnormalities in SALS are highly localized to the motor neuron enriched mRNA pool (the degenerating anatomic compartment) and not apparent in the anterior horn enriched mRNA pool (the surrounding microenvironment).
He started in a second key.
A second key area is innovation.
A second key area is distribution planning.
Education is a second key factor.
