Software Sizing Measures

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" rowspan="3" width=170 BGCOLOR="#000099" TEXT="#F7F7FF" background="02ebbc00erkqpg.jpg"> <div> <B><IMG BORDER="0" SRC="Symb075c00b700c8cccccc00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Software Sizing Measures</B></div> <div> <A HREF="req_conc.htm" TARGET="_top" TITLE="Requirements Concepts"><IMG BORDER="0" SRC="Symb075c00b700c8cccccc00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Requirements Concepts</A></div> <div> <A HREF="tr_as_size_meas.htm" TARGET="_top" TITLE="Testable Requirements as a Sizing Measur"><IMG BORDER="0" SRC="Symb075c00b700c8cccccc00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Testable Requirements as a Sizing Measure</A></div> <div> <A HREF="tr_appl.htm" TARGET="_top" TITLE="Applications of Testable Requirements"><IMG BORDER="0" SRC="Symb075c00b700c8cccccc00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Applications of Testable Requirements</A></div> <div> <A HREF="tr_exper.htm" TARGET="_top" TITLE="Experience With Testable Requirements"><IMG BORDER="0" SRC="Symb075c00b700c8cccccc00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Experience With Testable Requirements</A></div> <div> <A HREF="ref.htm" TARGET="_top" TITLE="References"><IMG BORDER="0" SRC="Symb075c00b700c8cccccc00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">References</A></div> <div> <A HREF="glossry.htm" TARGET="_top" TITLE="Glossary"><IMG BORDER="0" SRC="Symb075c00b700c8cccccc00.png" HEIGHT="13" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Glossary</A></div> </td> <td valign="top" colspan=2 height=60 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <B>Software Sizing Measures</B></div> <bR> <bR> <div> </div> </td> </tr><tr> <td valign="top" height=396 width="100%" colspan=2 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> Sizing measures are needed to make valid comparisons across (or within) systems.  Without a software sizing measure, productivity cannot be computed.  For example, the real estate industry has "square feet" and the oil industry has "barrels of oil" as standard measures.  In the computer software industry, however, software developers do not have a generally accepted measure of what they produce.</div> <bR> <div> While <I>estimating </I>is probably the most common use of a sizing measure, there are many other potentially valuable applications, including progress measurement, change management, risk identification, and <A HREF="earn_val.htm" TARGET="_top" TITLE="Earned Value">earned value</A>.</div> <bR> <div> There are only two software sizing measures widely used today -- Lines of Code (LOC or KLOC) and Function Points (FP).  Though each is a sizing measure, they actually measure different things and have very different characteristics.</div> <bR> <div> <I>Lines of Code</I> is a measure of the size of the system after it is built.  It is very dependent on the technology used to build the system, the system design, and how the programs are coded.  The major disadvantages of LOC are that systems coded in different languages cannot be easily compared and efficient code is penalized by having a smaller size.  Capers Jones stated at a talk to the Chicago Quality Assurance Association on November 22, 1996 that anyone using LOC is "<I>committing profession malpractice</I>."<FONT SIZE="1" COLOR="#000000" FACE="Arial" > <A HREF="ref_2__jones_capers_applied_software.htm" TARGET="_top" TITLE="References">[Ref 2]</A></FONT>  Despite these problems, LOC is still frequently used by very reputable and professional organizations.</div> <bR> <div> In contrast to LOC, <I>Function Points</I> is a measure of delivered functionality that is relatively independent of the technology used to develop the system.  FP is based on sizing the system by counting external components (inputs, outputs, external interfaces, files and inquiries.)  While FP addresses many of the problems inherent in LOC and has developed a loyal following, it has its own set of advantages and disadvantages (see Figure 1 below).  </div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <TABLE BORDER="2" CELLPADDING="1" CELLSPACING="1" WIDTH="560" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" BGCOLOR=#C0C0C0 > <tR> <tD VALIGN=TOP BGCOLOR=#C0DCC0 HEIGHT= 20 WIDTH="76"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="20" ALIGN="bottom" WIDTH="76" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP BGCOLOR=#C0DCC0 WIDTH="250"><div> <B>Advantages</B></div> </tD> <tD VALIGN=TOP BGCOLOR=#C0DCC0 WIDTH="214"><div> <B>Disadvantages</B></div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#C0DCC0 HEIGHT= 95 WIDTH="76"><div> <B>LOC</B></div> </tD> <tD VALIGN=TOP BGCOLOR=#C0DCC0><NOBR><div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Easy to compute</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Intuitive</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Granular</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Natural byproduct of process</div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#C0DCC0 WIDTH="214"><div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Penalizes efficient code</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Difficult to make valid comparisons across languages</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Dependent on technology</div> </tD> </tR> <tR> <tD VALIGN=TOP BGCOLOR=#C0DCC0 HEIGHT= 76 WIDTH="76"><div> <B>FP</B></div> </tD> <tD VALIGN=TOP BGCOLOR=#C0DCC0 WIDTH="250"><div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Measures system from user perspective</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Relatively independent of technology</div> </tD> <tD VALIGN=TOP BGCOLOR=#C0DCC0 WIDTH="214"><div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Requires specialized training to compute</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Not intuitive</div> <div> <IMG BORDER="0" SRC="Symb075c00b700f000000000.png" HEIGHT="16" WIDTH="24" ALIGN="bottom" HSPACE="0" VSPACE="0">Difficult to communicate</div> </tD> </tR> </TABLE></div> <bR> <div> <B>LOC and FP -- Advantages and Disadvantages</B></div> <div> Figure 1</div> <bR> <div> Because Lines Of Code and Function Points have been the only ways to size a system, a software developer's or project manager's choices have been very limited.  Most have opted not to measure at all.</div> </td> </tr><tr> <td valign="top" colspan=2 height=24 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <IMG BORDER="0" SRC="1x1.gif" HEIGHT="17" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" WIDTH="17"><B> </B><A HREF="req_conc.htm" TARGET="_top" TITLE="Requirements Concepts"><B><IMG SRC="02811110.png" border=0 width="17" height="17" ALT="next" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></A><B>     </B><A HREF="index.htm" TARGET="_top" TITLE="Sizing Software Using Testable Requireme"><B><IMG SRC="02611110.png" border=0 width="17" height="17" ALT="up" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></A><B> </B><IMG BORDER="0" SRC="1x1.gif" HEIGHT="17" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" WIDTH="17"><B>          </B><B>               </B><A HREF="http://www.mosaicinc.com" 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