Deconstructing the Computer Report of a Symposium (2005) / Chapter Skim
Currently Skimming:
II RESEARCH PAPER: Performance Measures for Computers--Jack E. Triplett
II RESEARCH PAPER: Performance Measures for Computers--Jack E. Triplett
Pages 97-140
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 99... ...
This paper provides a bridge between their interests. Section II explains, primarily to computer professionals, why economists want to measure computer performance and what economists do with performance measures.
|
From page 100... ...
Economists do not want to show an increase in computer performance as inflation. They want to measure computer inflation so that it is adjusted for changes in the performance of computers; in other words, computer inflation should be measured net of the performance premium.
|
From page 101... ...
1.0 1.5 1.8 Computer inflation 1.00 1.11 .96 (with estimated performance premium = 1 + .7 (M) Computer "constant price" output index 1.00 4.60 5.17 Computer output must have expanded by a factor greater than the threefold increase in units produced.
|
From page 102... ...
There are several reasons. An old computer relationship called Grosch's Law indicates that the cost of a computer center does not rise linearly with its computing power.
|
From page 103... ...
The "quality adjustment" outlined in the preceding paragraph is, in essence, the method applied by the Bureau of Labor Statistics (BLS) in estimating price indexes for computers, where quality adjustments for enhanced computer performance are derived from a hedonic function.
|
From page 104... ...
Getting from the price indexes to the output investment numbers is relatively straightforward and follows the example already presented. Table 2 shows current dollar changes for computer investment in the national accounts, the computer deflator, and the resulting deflated investment numbers from the national accounts, for the years 19952002.
|
From page 105... ...
Computer price indexes fall because the performance of computers is increasing very rapidly, where their actual selling prices are stable or falling. Accordingly, it is no surprise that computer output in the economy rises not so much because increasing numbers of computers are produced (though this is true)
|
From page 106... ...
1959 101372.4 0.000 1960 79593.2 0.00044 1961 58800.8 0.00077 1962 41710.3 0.00143 1963 27395.1 0.00396 1964 22916.4 0.00616 1965 18936.0 0.00979 1966 13272.8 0.02354 1967 10784.1 0.03091 1968 9202.6 0.03696 1969 8332.3 0.05038 1970 7484.4 0.0605 1971 5698.7 0.07458 1972 4592.4 0.11 1973 4354.0 0.12 1974 3554.9 0.15 1975 3288.5 0.15 1976 2746.5 0.23 1977 2390.1 0.34 1978 1616.8 0.66 1979 1339.7 1.07 1980 1045.6 1.69 1981 918.9 2.63 1982 822.3 3.24 1983 685.6 4.92 1984 554.6 8.04 1985 471.5 10.10 1986 406.2 11.61 1987 346.0 14.59 1988 321.4 16.67 1989 300.1 20.27 1990 272.3 20.03 1991 244.6 21.75 1992 209.2 29.40 1993 178.4 37.31 1994 157.3 46.00 1995 131.3 69.40 1996 100.0 100.00 1997 77.4 145.22 1998 57.0 208.39 1999 43.6 292.64 2000 37.9 347.77 2001 30.9 338.61 2002 26.3 400.92 SOURCE: Bureau of Economic Analysis, NIPA Table 7.6, and unpublished BEA data in possession of the author (with more precise quantity index for earlier years)
|
From page 107... ...
PERFORMANCE MEASURES FOR COMPUTERS 107 TABLE 4 Price Indexes for Domestic Mainframes and PCs (1996 = 100) Mainframes Personal Computers 1953 791125.1 1954 682645.1 1955 605330.6 1956 516628.7 1957 456095.6 1958 412943.3 1959 354208.3 1960 260717.8 1961 197440.1 1962 143811.5 1963 109881.7 1964 83549.6 1965 60060.6 1966 22761.6 1967 16110.6 1968 14560.0 1969 14513.8 1970 13967.4 1971 10847.4 1972 8871.7 1973 9453.9 1974 8041.6 1975 7771.7 1976 7106.5 1977 5582.2 1978 2812.2 1979 2306.9 1980 1591.9 1981 1311.4 1982 1106.3 1549.9 1983 1006.8 1086.5 1984 727.1 937.0 1985 537.1 877.3 1986 486.5 646.4 1987 419.1 582.9 1988 397.1 533.3 1989 346.5 496.1 1990 307.5 415.5 1991 297.6 350.4 1992 277.2 267.9 1993 234.2 207.3 1994 182.1 182.7 1995 144.0 145.3 1996 100.0 100.0 1997 68.6 67.1 1998 49.2 40.3 1999 38.6 25.7 2000 30.9 20.7 SOURCE: Triplett (1989)
|
From page 108... ...
, which greatly inhibits the ability to analyze recent productivity trends and the contribution of ICT investment in countries outside North America. In sections IIIV, I consider the variables that have been used as characteristics of computer performance in computer hedonic functions and the measures of computer performance that one would like to have for economic measurements.
|
From page 109... ...
. Economists were interested in a somewhat different but closely related problem: measuring performance-corrected price indexes for computers, using for the most part hedonic methods.
|
From page 110... ...
. Another intermediate-stage proxy measure is machine cycle time, also known as "clock speed." The execution time of the logical portion of any instruction equals machine cycle time multiplied by the number of machine cycles required for that instruction.
|
From page 111... ...
Indeed, one often saw MIPS speed measures quoted for personal computers in the early 1990s (e.g., Rosch, 1994, Table 3.1)
|
From page 112... ...
contains alternative indexes for peripheral equipment. The available price indexes for mainframe-era peripheral equipment are reviewed in Triplett (1989, Tables 4.11 and 4.12)
|
From page 113... ...
Though there was some sense that future research might incorporate true benchmark measures, in fact that never happened. Indeed, as explained in the subsequent section, when research on computers picked up again in the 1990s, the advance represented by synthetic benchmarking measures was almost entirely abandoned, and economists turned back to simple clock speed as their primary measure of computer performance.
|
From page 114... ...
. The performance variables in the IBM studies have provided the basis for most subsequent investigations on computer equipment, including price indexes for personal computers (which were actually not included in the IBM-BEA work)
|
From page 115... ...
These three points are developed in the following discussion. Component Performance Measures The variables used in three relevant IBM computer equipment hedonic functions are displayed in the first column of Annex Table B
|
From page 116... ...
All studies measure processor performance with speed and memory size, as did Dulberger (1989) , though nearly all of them measure speed with megahertz (a topic to which I return below)
|
From page 117... ...
And even more importantly: How much difference in the computer price indexes computed by BLS and others results from differences in the variables in the hedonic function? Performance Variables for PCs: The Dell Data A recent Dell catalog illustrates the complexity of the bundle of PC computer characteristics and the inadequacy of the representation of the computer in most existing PC hedonic functions.
|
From page 118... ...
This is not the place to explore what are essentially econometric problems in estimating hedonic functions. My own conclusion, from considerations that are developed elsewhere in the hedonic literature, is that omitted variable bias in hedonic price indexes and in measures of computer performance can be serious, and that omitted variables predominantly result in missing some of the improvement in computer performance, or what is the same thing, missing some of the decline in computer prices.
|
From page 119... ...
Benchmark measures have the advantage that they measure machine performance, rather than measuring some proxy for machine performance, or some input that may influence machine performance. Researchers who have tried to incorporate benchmark data into PC hedonic functions are Chwelos (2003)
|
From page 120... ...
He found that the relation between megahertz and performance differs across microprocessor generations.12 However, the price indexes he estimated differed trivially: An index using benchmarks declined 39.6 percent per year, and one using technical specifications declined 39.3 percent annually, where the indexes used otherwise comparable computational forms (see his Table XII)
|
From page 121... ...
In Triplett (1996) the specification of component inputs to the production of computers was very crude: Semiconductor price indexes that embodied price/ 14"Labor quality," for example, is composed of elements of human capital, with characteristics such as education, training, experience and so forth.
|
From page 122... ...
More recently, Aizcorbe, Flamm, and Khurshid (2002) have produced detailed price indexes for 12 classes of semiconductors and also produced consumption weights among these 12 classes for end uses, including computer production.
|
From page 123... ...
1986. "Quality-Adjusted Price Indexes for Computer Processors and Selected Peripheral Equipment." Survey of Current Business 66(1)
|
From page 124... ...
1994. "Hedonic Price Indexes for Spreadsheets and an Empirical Test for Network Externalities." RAND Journal of Economics 25.
|
From page 125... ...
2002. "Hedonic Price Analysis for Personal Computers in Australia: An Alternative Approach to Quality Adjustments in the Australian Price Indexes." Michaels, Robert.
|
From page 126... ...
2000. "Measuring the Price Development of Personal Computers in the Consumer Price Index." Paper for the Meeting of the International Hedonic Price Indexes Project.
|
From page 127... ...
Schneidewind Not specified Monthly rental 1. Memory size (thousands of characters)
|
From page 128... ...
Minimum memory size (thousands of bits) Characteristics Quarterly Stoneman British Published 1.
|
From page 129... ...
Memory size (maximum words in storage Ford (1976, (two sources) , monthly rental, available with particular CPU)
|
From page 130... ...
Dummy variables for manufacturers Cartwright, Auerbach Corp.; List prices, all 1. Speed (memory cycle time, machine cycle Donohoe, and Datapro Corp.; machines time, or MIPS, depending on period)
|
From page 131... ...
Machine cycle time (in nanoseconds regressions machines 2. Memory size (in megabytes)
|
From page 132... ...
Cache no no no no no Technology Chip dummies 16- or 32-bit 8-, 16- or 32- Processor Intel dummy variables processor bit processor type; chip chip dummies processor dummies type* MHz Disk (hard)
|
From page 133... ...
(INSEE) MHz MHz, Test score MIPS MHz MHz MHz^2 MB MB MB KB MB MB3 no no KB no no KB Processor Maximum Architecture no Celeron Chip type memory; dummy dummy dummies Apple*
|
From page 134... ...
plus microprocessor-type dummy variables and interactions between microprocessor type and clock speed. bReplaced by external volume measure.
|
From page 135... ...
PERFORMANCE MEASURES FOR COMPUTERS 135 Okamoto Lim and Statistics and Sato McKenzie van Mulligen Finland 2000 2001 2002 2002 MHz MHz CPU score MHz MB MB MB MB no no KB no Type dummy Processor no Processor type type GB MB MB GB no no no no no no no no Size Size 17 dummy no no no no no no no no no no No monitor no Dummy dummy; variable for LCD dummy presence no 4 9 3 no no no no
|
From page 136... ...
no no no no no Network card no no no no no Modem dummy no no no modem no speed Speakers dummy no no no no no Case type dummy no no no no no Warranty dummy no no no no no Seller dummies yes yes major major yes brand brand SCSI control no no no no no Operating system no no no no yes Other software no no no no other software utilities Other number of two or more battery type number of floppy drives floppy drives floppy dummy battery life drives slots available index for expansion size extended board density industry weight standard mobile discount architecture dummy density price bus discounted age weight number of by vendor slots age number of ports extra hardware
|
From page 137... ...
PERFORMANCE MEASURES FOR COMPUTERS 137 Rao and Pakes Moch Lynch Holdway Bourot no no no yes no no yes no no yes no no no no yes yes no no no no yes no no yes no yes no no no yes yes yes no yes yes yes no no yes no yes no no yes yes no no no yes no no yes no no yes no no no yes no Apple no yes yes no no no yes no no no yes no yes no no number of no software no bundled office suite; applications MS Office second number of business other floppy graphics market cards dummy standards bus width supported mouse dummy continued
|
From page 138... ...
138 DECONSTRUCTING THE COMPUTER ANNEX B2 Continued Evans Barzyk INSEE01 INSEE02 ZIP dummy no no no CDROM no no yes CDROM speed yes no no CDRW yes no no DVD dummy no no no Sound card dummy yes no no Video (MB) no yes no Network card yes no yes Modem dummy yes no yes Speakers dummy no no no Case-type dummy yes no yes Warranty dummy no yes no Seller dummies no yes yes SCSI control no no yes Operating system no no no Other software no no no Other number network of slots location
|
From page 139... ...
PERFORMANCE MEASURES FOR COMPUTERS 139 Okamoto Lim and and Sato McKenzie van Mulligen no no no no no no no no no no yes no no no no no no no no yes no no yes no yes no no no yes no no yes no no yes no Apple yes yes no yes no no no no no no no TV tuner expandability USB port vintage workstation dummies
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.