Why can imputation lead to bias in GWAS studies?

can you explain for me the lead time bias and length bias ?

list differences between photometric assays vs radiometric assays (hint towards alzheimer)

When performing QPCR to study differential gene expression, what is the role of SYBR green? What is the most correct answer? SYBRgreen intercalates proportionally and efficiently with double stranded DNA and can therefore be used to quantify it   SYBRgreen intercalates proportionally and efficiently with nucleic acids and can therefore be used to quantify them.   SYBRgreen intercalates more efficiently and proportionately with single stranded DNA and can therefore be used to quantify cDNA (a direct product of mRNA).   SYBRgreen intercalates proportionally efficiently with messenger RNA and can therefore be used to quantify it.