I didn't see your detailed calculation, but let's use this post to agree on the data. There is no way my calculation is wrong (since it's made by a sw), but there is the chance that I input the wrong probabilities. So, let's agree on that.
P(dad has HD a priori) = 0.5
P(a child has HD if a parent has it) = 0.5
P(a child has HD if no parent has it) = 0
P(having some symptom before age 54 if you have HD) = 0.8
P(having some symptom before age 54 if you don't have HD) = 0
P(having some symptom before age 34 if you have HD) = 0.67
P(having some symptom before age 34 if you don't have HD) = 0
Next you have this bit of information.
- Dad is 50/50 a priori to have HD and has 3 child
- Dad didn't have symptoms in his life and died at 54
- 1 child is assured 100% not having it because of a test
- 1 child didn't have symptoms till death, which happened at 34
- OP's wife, the 3rd child, didn't experience symptoms and she is currently 34
Is the above the correct statement of the problem?
Just in case one wants to use Netica. After download, copy/paste the following in a file with a .dne extension and load it into Netica through the File->Open menu.
Code:
// ~->[DNET-1]->~
bnet tptHD {
AutoCompile = TRUE;
autoupdate = TRUE;
whenchanged = 1596881098;
visual V1 {
defdispform = BELIEFBARS;
nodelabeling = TITLE;
NodeMaxNumEntries = 50;
nodefont = font {shape= "Arial"; size= 9;};
linkfont = font {shape= "Arial"; size= 9;};
ShowLinkStrengths = 1;
windowposn = (22, 22, 1126, 482);
resolution = 72;
drawingbounds = (1412, 720);
showpagebreaks = FALSE;
usegrid = TRUE;
gridspace = (6, 6);
NodeSet Node {BuiltIn = 1; Color = 0x00e1e1e1;};
NodeSet Nature {BuiltIn = 1; Color = 0x00f8eed2;};
NodeSet Deterministic {BuiltIn = 1; Color = 0x00d3caa6;};
NodeSet Finding {BuiltIn = 1; Color = 0x00c8c8c8;};
NodeSet Constant {BuiltIn = 1; Color = 0x00ffffff;};
NodeSet ConstantValue {BuiltIn = 1; Color = 0x00ffffb4;};
NodeSet Utility {BuiltIn = 1; Color = 0x00ffbdbd;};
NodeSet Decision {BuiltIn = 1; Color = 0x00dee8ff;};
NodeSet Documentation {BuiltIn = 1; Color = 0x00f0fafa;};
NodeSet Title {BuiltIn = 1; Color = 0x00ffffff;};
PrinterSetting A {
margins = (1270, 1270, 1270, 1270);
};
};
node Dad_Has_It {
discrete = TRUE;
states = (yes, no);
kind = NATURE;
chance = CHANCE;
parents = ();
probs =
// yes no
(0.5, 0.5);
whenchanged = 1596783726;
belief = (0.5, 0.5);
visual V1 {
center = (492, 168);
height = 1;
};
};
node Brother1 {
discrete = TRUE;
states = (yes, no);
kind = NATURE;
chance = CHANCE;
parents = (Dad_Has_It);
probs =
// yes no // Dad_Has_It
(0.5, 0.5, // yes
0, 1); // no ;
whenchanged = 1596783722;
belief = (0.25, 0.75);
visual V1 {
center = (288, 300);
height = 2;
};
};
node Wife {
discrete = TRUE;
states = (yes, no);
kind = NATURE;
chance = CHANCE;
parents = (Dad_Has_It);
probs =
// yes no // Dad_Has_It
(0.5, 0.5, // yes
0, 1); // no ;
whenchanged = 1596636266;
belief = (0.25, 0.75);
visual V1 {
center = (492, 294);
height = 4;
};
};
node Brother2 {
discrete = TRUE;
states = (yes, no);
kind = NATURE;
chance = CHANCE;
parents = (Dad_Has_It);
probs =
// yes no // Dad_Has_It
(0.5, 0.5, // yes
0, 1); // no ;
whenchanged = 1596636806;
belief = (0.25, 0.75);
visual V1 {
center = (774, 294);
height = 3;
};
};
node Symptoms_54 {
discrete = TRUE;
states = (yes, no);
kind = NATURE;
chance = CHANCE;
parents = (Dad_Has_It);
probs =
// yes no // Dad_Has_It
(0.8, 0.2, // yes
0, 1); // no ;
whenchanged = 1596783719;
belief = (0.4, 0.6);
visual V1 {
center = (774, 168);
height = 6;
};
};
node Symptoms_34_w {
discrete = TRUE;
states = (yes, no);
kind = NATURE;
chance = CHANCE;
parents = (Wife);
probs =
// yes no // Wife
(0.67, 0.33, // yes
0, 1); // no ;
whenchanged = 1596783721;
belief = (0.1675, 0.8325);
visual V1 {
center = (492, 402);
height = 7;
};
};
node Symptoms_34 {
discrete = TRUE;
states = (yes, no);
kind = NATURE;
chance = CHANCE;
parents = (Brother2);
probs =
// yes no // Brother2
(0.67, 0.33, // yes
0, 1); // no ;
whenchanged = 1596783718;
belief = (0.1675, 0.8325);
visual V1 {
center = (774, 396);
height = 5;
};
};
ElimOrder = (Brother1, Symptoms_54, Symptoms_34_w, Wife, Dad_Has_It, Brother2, Symptoms_34);
};
Last edited by nickthegeek; 08-08-2020 at 06:29 AM.