Trouble-some twos: The case of 'If' vs 'Then'

'If' should always be succeeded by 'then'

e.g. If the scientists analyzed the PCR data, then the gene expression could be determined.

Instead of: The scientists analyzed the PCR data to determine 𝗶𝗳 the genes were expressed.

Use: The scientists analyzed the PCR data to determine 𝘄𝗵𝗲𝘁𝗵𝗲𝗿 the genes were expressed.

'Whether' should always imply 'whether or not'

e.g. The gene expression can be determined depending on whether (or not) the scientists analyze the PCR data.