The phrase "a linear decline" is correct and usable in written English.
It can be used to describe a steady decrease in a particular variable over time or in a specific context.
Example: "The data shows a linear decline in sales over the past five years, indicating a consistent drop in consumer interest."
Alternatives: "a steady decrease" or "a gradual decline".
There was a linear decline in GRper with slope.
Analysis of birth weights showed a linear decline with increasing starting and finishing numbers.
Notably, the absolute population of children and adolescents showed a linear decline by 6.3% between 2008 and 2013.
The period 2001 to 2030 shows a linear decline in yields of around −0.2% p.a. and an R 2=0.16.
The recorded runoff at the Gaoshiya station of the Gushan River presents a significant decreasing trend with a linear decline rate of −1.541 mm/year.
The study revealed that the absorbed gas content of shale rises with increasing pressure under isothermal condition and exhibits a linear decline with increasing temperature under isobaric condition.
The EE application caused a linear decline (P<0.05) in LW gain of cows fed the sorghum supplement, but not in cows fed the barley supplement.
Results for SE showed that there was a linear decline over the 14-week course, although retrospective qualitative data from students suggested that they perceived their SE in writing to have increased.
Turning to party membership, Fig. 4 shows a linear decline in the likelihood of becoming adherents and a steady increase in that of becoming adventurers for both party members and non-party members.
Inclusion of maize silage in the diet resulted in a linear decline in the apparent digestibility of starch (P = 0.022), neutral detergent fibre (P < 0.001) and acid detergent fibre (P = 0.003).
In the medium stress treatment one response was u-shaped and one showed a linear decline in CVFG with increasing FGR.
