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It is the responsibility of all registered users of the Human Mortality
Database (HMD) to give proper credit to the institutions and/or individuals
who have created the data being provided or transmitted here. Proper
citation is necessary whether the data in question are quoted in formal
publications or in other contexts. The following comments are intended
to assist users by providing information about HMD data sources and
by offering suggestions for appropriate citation procedures. Please
note, however, that ultimate responsibility in these matters resides
with the user alone, under the terms of the User
Agreement.
It is important to distinguish between two types of data included in
the HMD. First, there are several kinds of raw data for each population,
which serve as inputs for all subsequent calculations. Second, there
are data of various sorts that are original to the HMD, having been
generated according to techniques that are fully described in our Methods
Protocol. In the former case, it is important to acknowledge the institutions
or individuals responsible for creating and/or publishing the raw data:
in these circumstances, the HMD is merely transmitting the data from
its source to the user. Thus, it is only in the second case that it
is appropriate to give credit to the HMD as the source (i.e., corporate
author) of the information provided here.
Identifying the
Correct Data Source
In future versions
of this database, we hope to develop better methods of informing users
about the source(s) of data included in the HMD. In the present version,
the user can successfully determine whether a particular number is being
transmitted from an external source or whether it is original to the
HMD by asking a number of questions:
- Is the number
taken from the Input Database of the HMD? At the bottom of every country
page, there is link labeled "Access to Raw Data". Through
this link, a user gains access to the raw data used in assembling
the data that are presented on each country page. All data in the
Input Database have been extracted from other sources, which are clearly
documented using a system of reference codes. The HMD should never
be cited as the source of such information, but only as an intermediary
that has transmitted the data from its source to the user.
- Is the number
taken from points 4 through 7 of a country page (i.e., exposure-to-risk,
death rates, life tables, or life expectancy at birth)? All such data
are original creations of the HMD, which should thus be cited as the
unique source of the information.
- Is the number
taken from point 1 of a country page (i.e., births)? All such data
come from an external source, and the HMD is merely transmitting the
information to the user. The user should identify and cite the original
source, merely acknowledging the HMD as the intermediary. There are
two ways of identifying the original source of such data. First, the
user may consult a complete list of sources for a given population by
means of a link called "Data sources" found at the bottom
of each country page. This list is organized by data type (births,
deaths, etc.). In most cases, the source of birth counts reported
in HMD should be readily apparent. However, if questions remain after
consulting this list, the user should consult the Input Database (through
the link called "Access to raw data" found at the bottom
of each country page), in which the source of every raw data point
is clearly noted.
- Is the number
taken from point 2 of a country page (i.e., deaths)? All such data
are derived from an external source, although the original numbers
may or may not have been manipulated in various ways before they appear
on a country page. For citation purposes, we must distinguish between
two cases:
- Some
death counts appear under point 2 of a country page without alteration.
Thus, they are identical to the information contained in the Input
Database, and the proper citation procedure is the one given above
for birth data. For death data by Lexis triangle, this case is
relatively rare: it occurs only when the original source contains
death counts classified by single-year age interval, year of occurrence,
and year of birth, and where there are no reports of deaths with
age unknown (for a given calendar year).
- Most
death counts appear under point 2 of a country page after various
alterations, which may be slight or substantial in nature. Briefly,
there are just two kinds of manipulations applied to raw death
counts in the HMD: i) assigning deaths of unknown age to specific
ages, and ii) splitting aggregate death counts (in various formats)
into data organized by Lexis triangle. In these situations, the
numbers are original creations of the HMD, which should thus be
acknowledged as the source of the data.
It is possible that data under point 2 of a given country page may
consist of one or both types of death counts (i.e., unaltered raw
data and/or original HMD estimates). The simplest method of distinguishing
between these two types is to observe whether a number contains some
fractional deaths. That is, raw data are expressed as a whole number
of deaths, whereas estimated death counts typically contain some fractional
element. This method is not infallible, as the fractional part of
an estimate could be zero just by chance: since death data are formatted
with 2 decimal points, this should occur at random with a frequency
of 0.01. However, by inspection of surrounding data points, there
should in general be no ambiguity about this issue. In cases of lingering
doubt, the user should consult the HMD Input Database and examine
the raw data directly.
- Is the number
taken from point 3 of a country page (i.e., population size)? For
ages 80 and above, population estimates reported on a country page
are always original creations of the HMD and should be cited accordingly.
Below age 80, however, population estimates shown in this location
may come directly from an external source, or they may be unique to
the HMD. As with death counts, it is possible to determine whether
a number comes from an external source or was created expressly for
the HMD by observing its decimal part: whole numbers usually indicate
that a number is taken from some other source, whereas a non-zero
fraction (i.e., anything other than "00" after the decimal
point) is a sign that the number is a product of the HMD itself.
Choosing a Bibliographic
Citation
As described above,
proper citation practice requires that a user should determine whether
numbers obtained through the HMD come from an external source or whether
such data are original creations unique to this database. If the user
concludes that the data in question should be attributed to the HMD
itself, we suggest the following format for a bibliographic citation:
Human Mortality
Database. University of California, Berkeley (USA), and Max Planck
Institute for Demographic Research (Germany). Available at www.mortality.org
or www.humanmortality.de
(data downloaded on [date]).
If you choose another
citation format, please be sure that it includes the full name of the
database (Human Mortality Database), the full names of both institutional
sponsors (University of California, Berkeley, and Max Planck Institute
for Demographic Research), and one or both of our Internet addresses,
www.mortality.org
or www.humanmortality.de.
For data from an
external source, which are merely transmitted via the HMD, the user
should choose an appropriate citation based on standard practice. The
citation given in the list of "Data sources" for each population
may be used as a guide, but it should not be considered authoritative.
It is appropriate in these situations to acknowledge the HMD as the
intermediary through which the data were obtained. For example, a bibliographic
citation for death counts in the United States might be as follows:
National Center
for Health Statistics. Vital Statistics of the United States,
Volume II: Mortality, Part A. Washington, D.C.: Government Printing
Office, various years. (Data obtained through the Human Mortality
Database, www.mortality.org
or www.humanmortality.de,
on [date].)
Finally, please
remember that proper citation of data obtained through the HMD is the
responsibility of the user alone, as stated clearly in the User Agreement.
However, if you still have questions or comments about citation procedures
after reading these guidelines, please write to us at hmd@mortality.org.
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