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. 2018 Feb 13;6(1):16. doi: 10.3390/healthcare6010016

Table 3.

Algebraic manipulation of previous equations.

We know that We know that
z = x * se + y * (1-sp) z = x * se + y * (1-sp)
y = p * x x = y / p
which means that which means that
z = x * se + p * x * (1 - sp) z = (y / p) * se + y * (1 - sp)
we solve for x we solve for y
x = z / (-sp * p + se + p) y = p * z / (-sp * p + se + p)
For the previous example with z = 100 000 and p= 2.5 we get
x = 215 054
y = 537 634
I have again written a udf in VBA
Lyme2(se ; sp ; p ; z ; output) where output is either "x", "y" or "zz"
Lyme2(0.44;0.99;2.5;100000;"x") x = 215 054
Lyme2(0.44;0.99;2.5;100000;"y") y = 537 634
Lyme2(0.44;0.99;2.5;100000;"zz") zz = 13.29
we know that we know that
zz = (z / (x + y)) * 100 zz = (z / (x + y)) * 100
y = p * x x = y / p
which means that which means that
zz = (z / (x + p * x)) * 100 zz = (z / ((y / p) + y)) * 100
we solve for x we solve for y
x = 100 * z / (p * zz + zz) y = 100 * p * z / (p * zz + zz)
For the previous example with z=100 000, zz =13.29 and p= 2.5 we get
x = 215 054
y = 537 634
I have again written a udf in VBA
Lyme3(se ; sp ; p ; z ; zz ; output) where output is either "x", "y"
Lyme3(0.44;0.99;2.5;100000;13.29;"x") x = 215 054
Lyme3(0.44;0.99;2.5;100000;13.29;"y") y = 537 634