From lobry at biomserv.univ-lyon1.fr  Mon Mar 31 18:18:20 2008
From: lobry at biomserv.univ-lyon1.fr (Jean lobry)
Date: Mon, 31 Mar 2008 18:18:20 +0200
Subject: [Rd] data(lh) time serie parameters
In-Reply-To: <971536df0803300436r6615feb2hc445b9e143edba14@mail.gmail.com>
References: <mailman.25.1206702006.15065.r-devel@r-project.org>	
	<p06002005c4150f9d2903@192.168.1.10>
	<971536df0803300436r6615feb2hc445b9e143edba14@mail.gmail.com>
Message-ID: <p06002003c416b509ee4c@[134.214.236.111]>

>
>It seems they are using 10 minutes as the unit of measurement.
>If you wish to change it to hours you might want to use this instead:
>
>    lh.hr <- ts(lh, start = 0, frequency = 6)
>
>so that
>
>    cycle(lh.hr)
>
>starts out at 1.

Dear Gabor,

yes, it is very likely that the original dataset was with a 10 minutes
unit of measurement because plot(lh[1:44]) yields the same curve as
figure 1b in:

@article{DigglePJ1991,
     title = {Nonparametric comparison of cumulative periodograms},
     author = {Diggle, P.J. and Fisher, N.I.},
     journal = {Applied Statistics},
     volume = {40},
     pages = {423-434},
     year = {1991}
}

whose legend reads:

QUOTE
Fig. 1. Four time series of LH concentrations in blood samples: each
series consists of $n = 44$ values derived from blood samples taken at
10-min intervals from a healthy adult female (data collected by Dr A.
Murdoch): a) early follicular phase, first cycle; (b) early follicular
phase, second cycle; (c) late follicular phase, first cycle; (d) late
follicular phase, second cycle
UNQUOTE

The complete multiple time series with 48 values as in data(lh) was
deposited in statlib by P.J. Diggle himself:
http://lib.stat.cmu.edu/datasets/diggle
(note that the first one has 4 trailling 0 that look like NA which
may explain why there were only 44 values in the 1991 paper).

What I found confusing is that

plot(lh)

ends at 48 when the doc says that lh is a "regular time series".
That would be OK for me if lh was a simple vector, but lh is a
time series so I would expect it to have different tsp() parameters
to fit the doc.

Best,

Jean
-- 
Jean R. Lobry            (lobry at biomserv.univ-lyon1.fr)
Laboratoire BBE-CNRS-UMR-5558, Univ. C. Bernard - LYON I,
43 Bd 11/11/1918, F-69622 VILLEURBANNE CEDEX, FRANCE
allo  : +33 472 43 27 56     fax    : +33 472 43 13 88
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[Rd] data(lh) time serie parameters
Jean lobry