Quality & Quantity (2005) 39:453–465 © Springer 2005
The Use of SPlus Software to Analyse Event
History Data: An Application to the Early
Career Promotion of Nurses in UK
CAROL DESOUSA and TREVOR MURRELLS
Birkbeck College, London, UK; Nursing Research Unit, Florence Nightingale School of
Nursing, King’s College London, London, UK.; E-mail: email@example.com
Abstract. This paper discusses the beneﬁts of using SPlus software to carry out longitudinal
analyses such as event history methods. An illustration is provided using three-year career
histories of a nationally drawn cohort of recently qualiﬁed registered nurses, who completed
a diploma programme in the UK between August 1997 and September 1998. For the pur-
poses of this paper, the time to ﬁrst promotion is examined using a Cox proportional haz-
ards model with a frailty term included, to allow for unobserved heterogeneity. The results
indicated that men have a slightly higher rate of promotion compared with women, and par-
ticularly when compared with women who took a maternity break during their early career.
Age is also a signiﬁcant factor, with younger cohort members being promoted at a higher
rate than their older colleagues. The inclusion of a frailty term to account for clustering at
the university level also signiﬁcantly improved the model. It is shown that SPlus, which is a
powerful, user-friendly statistical package, can be easily utilized by researchers to carry out
event history analysis as well produce high quality cumulative hazard and diagnostic plots
using its sophisticated graphics facilities.
Key words: SPlus, event history analysis, survival analysis, nursing, career promotion
Causality is at the heart of understanding social processes. The basic
assumption is that if A precedes B then A causes B. However, social pro-
cesses tend to be far more complex than this. The combination of many
explanatory factors, occurring together at one time point or in a series of
events, may lead to the outcome B. Alternatively B may affect A which
in turn then affects B. For example, taking a maternity break may delay
career promotion or alternatively a delay in promotion may strongly inﬂu-
ence an individual’s decision to take a maternity break.
Author for correspondence: Nursing Research Unit, King’s College London, James
Clerk Maxwell Building, 57 Waterloo Road, London SE1 8WA, U.K.