กระดาษที่มีต้นกำเนิดจาก Wedderburn ใน 74 คือการอ่านที่ดีเกี่ยวกับเรื่องของ quasilikelihood โดยเฉพาะอย่างยิ่งเขาสังเกตว่าสำหรับครอบครัวชี้แจงปกติการแก้สมการความน่าจะเป็นที่ได้รับจากการแก้สมการคะแนนทั่วไปของรูปแบบ:
0 = ∑i=1nS(β,Xi,Yi)=DTW(Y−g−1(XTβ))
Where D=∂∂βg−1(XTβ) and W=V−1. This notation originates in the work of McCullogh and Nelder in the originating text, "Generalized Linear Models". M&N describe solving these types of functions using the Gauss Newton type algorithm.
Interestingly, however, this formulation hearkened to a method-of-moments type estimator where one could simply sort of "set the thing they want to estimate" in the RHS of the parenthesized expression, and trust that the expression would converge to "that interesting thing". It was a proto form of estimating equations.
Estimating equations were no new concept. In fact, attempts as far back as 1870s and early 1900s to present EEs correctly derived limit theorems from EEs using Taylor expansions, but a lack of connection to a probabilistic model was a cause of contention among critical reviewers.
Wedderburn showed a few very important results: that using the first display in a general framework where the score equation S can be replaced by a quasiscore, not corresponding to any probabilistic model, but instead answering a question of interest, yielded statistically cogent estimates. Reverse transforming a general score resulted in a general qMLE which comes from a likelihood that is correct up to a proportional constant. That proportional constant is called the "dispersion". A useful result from Wedderburn is that strong departures from probabilistic assumptions can result in large or small dispersions.
However, in contrast to the answer above, quasilikelihood has been used extensively. One very nice discussion in McCullogh and Nelder deals with population modeling of horseshoe crabs. Not unlike humans, their mating habits are simply bizarre: where many males may flock to a single female in unmeasured "clusters". From an ecologist perspective, actually observing these clusters is far beyond the scope of their work, but nonetheless arriving at predictions of population size from catch-and-release posed a significant challenge. It turns out that the this mating pattern results in a Poisson model with significant under-dispersion, that is to say the variance is proportional, but not equal to the mean.
Dispersions are considered nuisance parameters in the sense that we generally do not base inference about their value, and jointly estimating them in a single likelihood results in highly irregular likelihoods. Quasilikelihood is a very useful area of statistics, especially in light of the later work on generalized estimating equations.