# Vectorcardiography Data

The set of vectorcardiogram data described in Downs, Liebman and Mackay (1974) is a classic data set on the rotation group SO(3).

The data set summarises vectorcardiograms of 98 normal children aged 2-19. Each child has data from two vectorcardiograms: one using the Frank system for electrical lead placement, the other using the McFee lead system. Each vectorcardiogram has 3 unit vectors associated with it. They are:
q: the spatial direction of the vector of the QRS loop having the greatest magnitude,
p: the unit vector perpendicular to QRS and to the 'QRS plane' (the plane containing the QRS loop),
t: the spatial direction of the vector of the T loop having the greatest magnitude.
A more detailed explanation of these vectors is given in Section 2 of Downs, Liebman and Mackay (1974).
The vectors q and p are orthogonal and the frame (q, p) gives the orientation of the QRS loop.

The data are made available by kind permission of Professor T.D. Downs.

In the worksheet, the unit vectors q, p and t are expressed in rectangular x,y,t coordinates to five decimal places. These coordinates are identified numerically as x=1, y=2 and t=3;
the lead systems are identified by F and M for the Frank and McFee systems, respectively;
and the unit vectors q, p and t are identified by QRS, PRP and T, respectively.
For example, column E is labelled FQRS3 and is thus the t coordinate of the QRS vector for the Frank lead system.

The age-sex groupings used in column B are:
1: 28 boys aged 2-10
2: 28 boys aged 11-19
3: 17 girls aged 2-10
4: 25 girls aged 11-19.

Downs, T., Liebman, J. and Mackay, W. (1974). Statistical methods for vectorcardiogram orientations. In Vectorcardiography 2: Proc. XIth International Symposium on Vectorcardiography (I. Hoffman, R.I. Hamby and E. Glassman, Eds.) 216-222. North-Holland, Amsterdam.