Mercurial > hg > camir-aes2014
diff toolboxes/FullBNT-1.0.7/bnt/examples/limids/amnio.m @ 0:e9a9cd732c1e tip
first hg version after svn
author | wolffd |
---|---|
date | Tue, 10 Feb 2015 15:05:51 +0000 |
parents | |
children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/toolboxes/FullBNT-1.0.7/bnt/examples/limids/amnio.m Tue Feb 10 15:05:51 2015 +0000 @@ -0,0 +1,135 @@ + +clear all +B0 = 1; Rtriple = 2; Damnio = 3; +B1 = 4; Ramnio = 5; Dabort = 6; +B2 = 7; U = 8; + +N = 8; +dag = zeros(N,N); +dag(B0, [Rtriple B1 Ramnio]) = 1; +dag(Rtriple, [Damnio Dabort]) = 1; +dag(Damnio, [B1 Ramnio]) = 1; +dag(B1, B2) = 1; +dag(Ramnio, [Dabort U]) = 1; +dag(Dabort, B2) = 1; +dag(B2, U) = 1; + + + +ns = zeros(1,N); +ns(B0) = 2; +ns(B1) = 3; +ns(B2) = 4; +ns(Rtriple) = 2; +ns(Ramnio) = 3; +ns(Damnio) = 2; +ns(Dabort) = 2; +ns(U) = 1; + +limid = mk_limid(dag, ns, 'chance', [B0 B1 B2], ... + 'decision', [Damnio Dabort], 'utility', [U]); + +% states of nature +healthy = 1; downs = 2; miscarry = 3; aborted = 4; +% test results +pos = 1; neg = 2; unk = 3; +% actions +yes = 1; no = 2; + +% Prior probability baby has downs syndrome +tbl = zeros(2,1); +p = 1/1000; % from www.downs-syndrome.org.uk figure +p = 24/10000; % www-personal.umich.edu/~bobwolfe/560/review/Downs.pdf (for women agen 35-40) +tbl(healthy) = 1-p; +tbl(downs) = p; +limid.CPD{B0} = tabular_CPD(limid, B0, tbl); + +% Reliability of triple screen test +% Unreliable sensor +% B0 -> Rtriple +tbl = zeros(2,2); % Rtriple = pos, neg +p = 0.5; % high false positive rate (guess) +tbl(healthy, :) = [p 1-p]; +p = 0.6; % low detection rate (march of dimes figure) +tbl(downs, :) = [p 1-p]; +limid.CPD{Rtriple} = tabular_CPD(limid, Rtriple, tbl); + +limid.CPD{Damnio} = tabular_decision_node(limid, Damnio); + +% Effect of amnio on baby B0,Damnio -> B1 + % 1/200 risk of miscarry +p = 1/200; % (march of dimes figure) +tbl = zeros(2, 2, 3); % B1 = healthy, downs, miscarry +tbl(healthy, no, :) = [1 0 0]; +tbl(downs, no, :) = [0 1 0]; +tbl(healthy, yes, :) = [1-p 0 p]; +tbl(downs, yes, :) = [0 1-p p]; +limid.CPD{B1} = tabular_CPD(limid, B1, tbl); + +% Reliability of amnio B0, Damnio -> Ramnio +% Perfect sensor +tbl = zeros(2,2,3); % Ramnio = pos, neg, unk +tbl(:, no, :) = repmat([0 0 1], 2 ,1); +tbl(healthy, yes, :) = [0 1 0]; +tbl(downs, yes, :) = [1 0 0]; +limid.CPD{Ramnio} = tabular_CPD(limid, Ramnio, tbl); + +limid.CPD{Dabort} = tabular_decision_node(limid, Dabort); + +% Effect of abortion on baby B1, Dabort -> B2 +tbl = zeros(3, 2, 4); % B2 = healthy, downs, miscarry, aborted +tbl(:, yes, :) = repmat([0 0 0 1], 3, 1); +tbl(healthy, no, :) = [1 0 0 0]; +tbl(downs, no, :) = [0 1 0 0]; +tbl(miscarry, no, :) = [0 0 1 0]; +limid.CPD{B2} = tabular_CPD(limid, B2, tbl); + +% Utility U(Ramnio, B2) +tbl = zeros(3, 4); +tbl(:, healthy) = 5000; +tbl(:, downs) = -50000; +tbl(:, miscarry) = -1000; +tbl(:, aborted) = -1000; + +if 0 +%tbl(unk, miscarry) = 0; % this case is impossible +tbl(pos, miscarry) = -1; +tbl(neg, miscarry) = -1000; +if 1 + tbl(unk, aborted) = -100; + tbl(pos, aborted) = -1; + tbl(neg, aborted) = -500; +else % pro-life utility fn + tbl(unk, aborted) = -500000; + tbl(pos, aborted) = -500000; + tbl(neg, aborted) = -500000; +end +end + +limid.CPD{U} = tabular_utility_node(limid, U, tbl); + + + +engine = jtree_limid_inf_engine(limid); +[strategy, MEU] = solve_limid(engine); + +% Rtriple U(Damnio=1=yes) U(Damnio=2=no) +% 1=pos 0 1 +% 2=neg 0 1 +dispcpt(strategy{Damnio}) +if isequal(strategy{Damnio}(1,:), strategy{Damnio}(2,:)) + % Rtriple result irrelevant + doAmnio = argmax(strategy{Damnio}(1,:)) +else + doAmnio = 1; +end + +% Rtriple Ramnio U(Dabort=yes=1) U(Dabort=no=2) +% 1=pos 1=pos 1 0 +% 2=neg 1=pos 1 0 +% 1=pos 2=neg 0 1 +% 2=neg 2=neg 0 1 +% 1=pos 3=unk 0 1 +% 2=neg 3=unk 0 1 +dispcpt(strategy{Dabort}) +