The phrase "a substantial decrease in the proportion" is correct and usable in written English.
It can be used when discussing statistical changes or trends, particularly in contexts such as research, reports, or analyses.
Example: "The study revealed a substantial decrease in the proportion of participants who reported experiencing anxiety over the past year."
Alternatives: "a significant reduction in the percentage" or "a considerable drop in the ratio."
In this study, we observed a substantial decrease in the proportion of extrapulmonary among all cases with age, clearly among both male and female patients in Cambodia and clearly among female patients in Viet Nam.
At 26°, H1 depletion resulted in a substantial decrease in the proportion of Cy + progeny (to ∼52% of the expected Mendelian ratio indicating approximately three-fold decrease in viability, relative to the unaffected siblings).
Compared with miR-control cells, miR-646 overexpressing cells and NOB1 silencing cells showed a substantial decrease in the proportion of cells in S phase and an increase in the number of cells in G1 phase in 786-O and ACHN cell lines.
It should be emphasized that the decrease in the proportion of patients that develop pneumonia should also result in a substantial decrease in the overall use of systemically administered antibiotics.
"This has, in turn, affected consumer spending and business growth, resulting in a substantial decrease in the UK's GDP.
Our results show a substantial decrease in the mortality rate.
However, among women there was a substantial decrease in endorsement of the term 'very overweight' from 2007 to 2012, and corresponding increases in the proportion of obese women describing themselves as either 'overweight' or 'about right'.
Substantial decreases in the proportion of households applying pesticides (25 to 11%) or hiring lawn care companies for application (15 to 5%) occurred.
The increased proportions of these cells was balanced by a substantial decrease in mature erythroid cells, as determined by histology (data not shown).
"This is a substantial decrease in arms agreements values over 2000, and is the first time since 1997 that total arms agreements decreased from the previous year," Mr. Grimmett wrote.
