Placement Targeting - Opt for it or Not !

Ever since Google has started Placement targeting (earlier called Site targeting) on CPC bidding basis, people started shifting from Content to this mode of targeting thinking it to be a safer bidding option. However, through experience and analysis I have learnt it is just the Reverse. Let us evaluate.

Assuming every w/s in content targeting has probability of conversion,

a<> a, in placement targeted campaign

Hence, P(Cp) - P(Cc)> b - a

or P(Cp) - P(Cc) > 0, Which means presumed enhanced click quality,

Assuming, Number of clicks = N, in original content targeted campaign, limited by budget(B)

So, Cc = N x P(Cc), and
Cp = n x P(Cp), which from earlier deductions
Cp - Cc = n x P(Cp) - N x P(Cc)


Observation : n < N, occurs in a large number of cases either due to bid going higher which is normal because, limiting exposure of ad, you force them to appear on same span, which reduces P(cp) value too. and quality score too decreases. ad placed to choose context within the closed domain which is lesser relevant than what it would have chosen in the open domain case in content targeted campaign.

Cp - Cc < 0,

So, Placement targeting actually Reduces your Conversion rate !!!