and starting salaries. The sample under investigation is drawn from ARL libraries. Cross-sectional data from 10 years (19891998) are analyzed using standard and widely accepted econometric techniques and procedures.
explorations of this issue are beyond the scope of this study but merit research.
Approximately 35% of the library heads held the title of Dean. (Other reported titles included Director, University Librarian, and one Vice Provost.) The role of a dean is unique in the academic organizational structure. Some have argued that serving as a dean enables the library to better serve the university population and enhances the perception of library faculty as members of the university faculty community (ALA, 2003).
Table 7A. Variable Means: 1989–1993 (N¼78).
Variable 1989 1990 1991 1992 1993
SALARY 21222.70 22426.35 23773.01 24572.83 25344.81
(2360.35) (2324.66) (2293.52) (2648.83) (2567.01)
TENURE 0.4359 0.4359 0.4359 0.4359 0.4359
(0.4991) (0.4991) (0.4991) (0.4991) (0.4991)
UNION 0.2308 0.2308 0.2308 0.2308 0.2308
(0.4241) (0.4241) (0.4241) (0.4241) (0.4241)
RESEARCH 0.3467 0.3467 0.3467 0.3467 0.3467
(0.4791) (0.4791) (0.4791) (0.4791) (0.4791)
FACULTY STATUS 0.3333 0.3333 0.3333 0.3333 0.3333
(0.4745) (0.4745) (0.4745) (0.4745) (0.4745)
DEAN 0.3462 0.3462 0.3462 0.3462 0.3462
(0.4788) (0.4788) (0.4788) (0.4788) (0.4788)
AGE 35.41 36.41 37.41 38.41 39.41
(18.99) (18.99) (18.99) (18.99) (18.99)
EXPEND 4092783.22 4395788.40 4715938.68 4903232.05 5193420.87
(1541772.95) (1683102.43) (1817614.31) (18622185.69) (2013030.71)
% PROFESSIONALS 0.2657 0.2661 0.2663 0.2687 0.2696
(0.0380) (0.0377) (0.0380) (0.0419) (0.0438)
VOLS 2928277.05 3001425.83 3109016.85 3183586.95 3281936.77
(1883240.24) (1912773.02) (1957872.94) (1994983.08) (2015630.29)
TYPE 0.3333 0.3333 0.3333 0.3333 0.3333
(0.4745) (0.4745) (0.4745) (0.4745) (0.4745)
MLS PROGRAM 0.2436 0.2436 0.2436 0.2436 0.2436
(0.4320) (0.4320) (0.4320) (0.4320) (0.4320)
FACULTY 1339.08 1371.85 1401.10 1473.78 1419.08
(489.30) (491.86) (513.62) (585.04) (565.53)
PHD FIELDS 58.36 57.26 58.05 57.64 58.49
(27.3861) (25.4795) (25.4568) (23.9577) (23.8332)
URBAN 0.7564 0.7564 0.7564 0.7564 0.7564
(0.4320) (0.4320) (0.4320) (0.4320) (0.4320)
NORTH 0.2179 0.2179 0.2179 0.2179 0.2179
(0.4155) (0.4155) (0.4155) (0.4155) (0.4155)
SOUTH 0.3077 0.3077 0.3077 0.3077 0.3077
(0.4645) (0.4645) (0.4645) (0.4645) (0.4645)
MIDWEST 0.2564 0.2564 0.2564 0.2564 0.2564
(0.4395) (0.4395) (0.4395) (0.4395) (0.4395)
WEST 0.2179 0.2179 0.2179 0.2179 0.2179
(0.4155) (0.4155) (0.4155) (0.4155) (0.4155)
The percentage of professionals fluctuated minimally during the time period under study, ranging from 27 to 28%. Other variables, such as VOLS and EXPEND, measure the total number of volumes and expenditures, which tended to rise over the sample period. SALARY reports the mean salaries for the time period under study; note that LSALARY uses the natural logarithm of the reported starting salaries. During this time period starting salaries went from $21,222 in 1989 to $30,619 in 1998, in nominal terms.
A number of variables reflect the characteristics of the university. Thirty- three percent of the institutions were privately funded and 67% were public institutions. Twenty-four percent of the sample institutions had a Library
Table 7B. Variable Means: 1994–1998 (N¼78).
Variable 1994 1995 1996 1997 1998
SALARY 25925.38 27633.46 28606.54 29375.05 30619.44
(2416.22) (2552.01) (2621.69) (2563.43) (2905.04)
TENURE 0.4359 0.4359 0.4359 0.4359 0.4359
(0.4991) (0.4991) (0.4991) (0.4991) (0.4991)
UNION 0.2308 0.2308 0.2308 0.2308 0.2308
(0.4241) (0.4241) (0.4241) (0.4241) (0.4241)
RESEARCH 0.3467 0.3467 0.3467 0.3467 0.3467
(0.4791) (0.4791) (0.4791) (0.4791) (0.4791)
FACULTY STATUS 0.3333 0.3333 0.3333 0.3333 0.3333
(0.4745) (0.4745) (0.4745) (0.4745) (0.4745)
DEAN 0.3462 0.3462 0.3462 0.3462 0.3462
(0.4788) (0.4788) (0.4788) (0.4788) (0.4788)
AGE 40.41 41.41 42.41 43.41 44.41
(18.99) (18.99) (18.99) (18.99) (18.99)
EXPEND 5446266.83 5804968.87 6141166.32 6486586.31 6870925.01
(2148519.06) (2251562.11) (2396245.26) (2614849.99) (2861764.37)
% PROFESSIONALS 0.2677 0.2697 0.2706 0.2718 0.2762
(0.0452) (0.0466) (0.0479) (0.0523) (0.0556)
VOLS 3381733.96 3469798.38 3551291.21 3630706.32 3710892.73
(2039786.22) (2071826.27) (2111995.33) (2152797.76) (2191169.64)
TYPE 0.3333 0.3333 0.3333 0.3333 0.3333
(0.4745) (0.4745) (0.4745) (0.4745) (0.4745)
MLS PROGRAM 0.2436 0.2436 0.2436 0.2436 0.2436
(0.4320) (0.4320) (0.4320) (0.4320) (0.4320)
FACULTY 1433.47 1416.55 1413.88 1415.46 1415.36
(572.83) (554.96) (568.90) (571.08) (577.27)
PHD FIELDS 57.86 57.91 56.97 57.27 57.06
(23.9820) (24.0104) (22.1728) (21.7002) (21.6366)
URBAN 0.7564 0.7564 0.7564 0.7564 0.7564
(0.4320) (0.4320) (0.4320) (0.4320) (0.4320)
NORTH 0.2179 0.2179 0.2179 0.2179 0.2179
(0.4155) (0.4155) (0.4155) (0.4155) (0.4155)
SOUTH 0.3077 0.3077 0.3077 0.3077 0.3077
(0.4645) (0.4645) (0.4645) (0.4645) (0.4645)
MIDWEST 0.2564 0.2564 0.2564 0.2564 0.2564
(0.4395) (0.4395) (0.4395) (0.4395) (0.4395)
WEST 0.2179 0.2179 0.2179 0.2179 0.2179
(0.4155) (0.4155) (0.4155) (0.4155) (0.4155)
Science graduate program with a master’s degree accredited by the ALA (as of the data collection date, August 2001). The mean number of institutional faculty ranged from 1,339 in 1989 to 1,415 in 1998. The mean number of doctoral programs supported by the universities in the sample fluctuated slightly over time, ranging from 56 to 57.
Other variables examine the geographic aspects of the universities’
location. Seventy-five percent of the responding institutions were located in metropolitan statistical areas, as defined by the Census Bureau. Twenty-two percent of the institutions were located in the North, 30% in the South, 25%
in the Midwest, and 21% in the West. Southern institutions are slightly overrepresented in the study. (This may reflect willingness to participate in a study generated from a researcher at a Southern institution.) Recall that Table 3reports participating institutions by region.
Table 8reports the minimum and maximum values for a selected year of the study, 1994. This year was selected as representative of the study and used for several diagnostic statistics discussed below. Table 8 illustrates some of the wide range of libraries and universities included, even within an elite group such as ARL. The minimum starting salary in 1994 was $21,000, while the maximum was $33,312.
Table 8. Minimum and Maximum Variable Values, 1994.
Variable Minimum Value Maximum Value
SALARY $21,000 $33,312
TENURE 0 1
UNION 0 1
RESEARCH 0 1
FACULTY STATUS 0 1
DEAN 0 1
AGE 6 62
EXPEND $2,148,519.06 $14,378,067.00
%PROFESSIONALS 0.1809 0.4344
VOLS 1,553,346 12,877,360
TYPE 0 1
MLS PROGRAM 0 1
FACULTY 448 3,193
PHD FIELDS 13 137
URBAN 0 1
NORTH 0 1
SOUTH 0 1
MIDWEST 0 1
WEST 0 1
Likewise, the range for expenditures is impressive: the minimum was a little over 2.1 million dollars, while the maximum was in excess of 14 million dollars.
Probability of Tenure Model
Tables 9A and 9Breport the results of the probit analysis for Model 1. The probit model examines the library and institutional characteristics that determine the probability that a university offers tenure track academic
Table 9A. Model 1: Probit Results: 1989–1993 (Dependent Variable¼TENURE,N¼78).
Variable 1989 1990 1991 1992 1993
CONSTANT 0.2596 0.2218 0.2321 0.7694 0.8480
(1.6871) (1.7489) (1.6580) (1.6596) (1.6221)
UNION 0.3563 0.3962 0.3384 0.5127 0.4648
(0.5479) (0.5517) (0.5566) (0.5278) (0.5392)
RESEARCH 1.007 1.1655 1.0770 1.1161 1.1646
(0.3980) (0.4119) (0.3979) (0.3900) (0.3944)
% PROFSTAFF 1.8232 3.0306 4.7411 3.3264 0.8642
(5.5662) (5.4057) (5.4815) (4.8400) (4.7564)
DEAN 1.0777 1.1483 1.1525 0.9921 1.0476
(0.4200) (0.4354) (0.4176) (0.4234) (0.4257)
AGE 0.0212 0.0203 0.0205 0.0199 0.0167
(0.0132) (0.0131) (0.0138) (0.0140) (0.0138)
ARL1 0.1880 0.7807 0.4941 0.1702 0.7003
(0.4844) (0.5089) (0.5501) (0.5401) (0.5540)
MLS PROGRAM 0.5099 0.5711 0.6657 0.6476 0.7659
(0.4280) (0.4331) (0.4421) (0.4287) (0.4440)
TYPE 0.0013 0.0321 0.1910 0.0170 0.1075
(0.5405) (0.5635) (0.5619) (0.5437) (0.5601)
FACULTY 0.6561E03 0.8913E03 0.7947E03 0.2622E03 0.6177E03
(0.0004) (0.0005) (0.0004) (0.0003) (0.0004)
URBAN 0.0628 0.1106 0.0889 0.1156 0.1501
(0.4459) (0.4415) (0.4344) (0.4250) (0.4382)
SOUTH 0.5645 0.5404 0.4879 0.5966 0.6546
(0.5547) (0.5782) (0.5718) (0.5563) (0.5592)
MIDWEST 0.0146 0.0730 0.0182 0.0866 0.0920
(0.5671) (0.6056) (0.5941) (0.5686) (0.5725)
WEST 0.1777 0.0755 0.1530 0.3841 0.2935
(0.6021) (0.6080) (0.6028) (0.5929) (0.5871)
PseudoR2 0.85 0.83 0.86 0.83 0.87
Note:( ): Standard errors.
Statistically significant at the .10 level, one-tailed test.
Statistically significant at the .05 level, one-tailed test.
Statistically significant at the .01 level, one-tailed test.
positions to librarians. While other studies have examined salaries and wage determination in academic libraries, no prior study has addressed this aspect of tenure in academic libraries.
The results for the 10 years are considerably stable. The pseudo R2(the percent of correct predictions) ranges from 81 to 87%. Some of the weakest results are seen in the last year of the study, 1998, as was also true for the OLS model discussed below. This time, however, there are variables that are consistently statistically significant throughout the 10 years. RESEARCH, which measured whether or not academic librarians had a research expectation as part of their appointment, was consistently statistically significant at the .01 level using a one-tailed test. RESEARCH was
Table 9B. Model 1: Probit Results: 1994–1998 (Dependent Variable¼TENURE,N¼78).
Variable 1994 1995 1996 1997 1998
CONSTANT 1.289 0.7738 0.2894 0.6683 1.3562
(1.5635) (1.5408) (1.5326) (1.3708) (1.4359)
UNION 0.4459 0.3757 0.4143 0.4039 0.4367
(0.5399) (0.5419) (0.5416) (0.5352) (0.5507)
RESEARCH 1.1651 1.1091 1.1102 1.1341 1.1515
(0.3947) (0.3910) (0.3902) (0.3957) (0.3979)
% PROFSTAFF 3.0374 2.4335 0.2035 1.9510 4.5809
(4.3598) (4.3597) (4.3299) (3.7021) (3.7393)
DEAN 1.0080 0.9675 0.9411 0.9993 0.9781
(0.4160) (0.4085) (0.3975) (0.4064) (0.4094)
AGE 0.0154 0.0211 0.0163 0.0273 0.0217
(0.0140) (0.0145) (0.0137) (0.0141) (0.0142)
ARL1 0.6191 0.1015 0.4322 0.3269 0.3967
(0.5859) (0.6011) (0.5467) (0.5318) (0.5434)
MLS PROGRAM 0.7366 0.5900 0.6817 0.1635 0.7032
(0.4403) (0.4257) (0.4363) (0.4301) (0.4312)
TYPE 0.1857 0.1876 0.1149 0.0395 0.0404
(0.5371) (0.5375) (0.5343) (0.5226) (0.5324)
FACULTY 0.5293E03 0.3723E03 0.3630E03 0.2351E03 0.1642E03
(0.0004) (0.0004) (0.0003) (0.0003) (0.0004)
URBAN 0.1931 0.2231 0.1528 0.0649 0.0569
(0.4423) (0.4277) (0.4256) (0.4252) (0.4206)
SOUTH 0.6457 0.5532 0.5745 0.5493 0.5212
(0.5519) (0.5437) (0.5460) (0.5501) (0.5536)
MIDWEST 0.1199 0.0028 0.1038 0.0181 0.7372
(0.5744) (0.5731) (0.5708) (0.5799) (0.5789)
WEST 0.2876 0.2455 0.2591 0.3966 0.4408
(0.5837) (0.5828) (0.5894) (0.5915) (0.5958)
PseudoR2 0.83 0.85 0.81 0.81 0.81
Note:( ): Standard errors.
Statistically significant at the .10 level, one-tailed test.
Statistically significant at the .05 level, one-tailed test.
Statistically significant at the .01 level, one-tailed test.
hypothesized to be positive and the results for 1989–1998 are consistently positive for this variable. This is not a surprising finding, given the centrality of research to many tenure track positions. While there are certainly some colleges and universities where research is not a defining element of the typical tenure track appointment, this was an expectation for the ARL member libraries and their institutions. As mentioned earlier, ARL libraries are found at some of the nation’s top research universities. Tenure at these institutions is more likely to be heavily weighted toward the research requirement. While academic librarianship does not necessarily or routinely have research expectations as part of the position description, tenure track positions are more likely to carry this requirement.
Also consistently statistically significant and positive at the .01 level is the variable DEAN. As Gorman mentioned in his debate inAmerican Libraries, some heads of libraries consider carrying the title of ‘‘Dean’’ to be an important element both for the viability of the library program and in establishing the parity of library faculty with other faculty members across campus (American Library Association, 2003).
AGE, which measures the years of ARL membership, was hypothesized to be negative. The probit model finds AGE to be statistically significant for 9 of the 10 years (omitting only 1994), although the level of statistical significance varies somewhat. The a priori assumption of a negative sign was confirmed and consistent. Older ARL member libraries are often seen to be the most traditional of research libraries and may have been more resistant to change when the new standards for tenure in academic libraries were introduced in the 1970s. Chressanthis (1994) offers an alternative inter- pretation, suggesting that older, more established research universities with higher standards for tenure may be less likely to have tenure track academic librarians. This is not entirely supported by another variable, ARL1, which measures the ARL library’s placement within the top 25% of the ARL libraries, based on the membership criteria index. While this variable carries the expected negative sign for 9 of the 10 years, it is statistically significant for only two years: 1990 and 1993.
As expected, MLS PROGRAM is positive for all 10 years and statistically significant for 9 of the 10. While the expected sign is positive, the strength and consistency of the relationship is somewhat surprising. It may be that the presence of faculty members in a graduate library science program strengthens the argument for tenure track positions in the library. This synergy between tenure in academic librarianship and library science education has not been explored in the literature and may offer an area ripe for future exploration.
FACULTY is statistically significant for five of the years under study and positive, as predicted. FACULTY measures the number of full-time faculty members at the institution. The variable is not significant for the years 1995–
1998, perhaps indicating a shift in the funding priorities of universities at the end of the 1990s.
The only other variable to show statistical significance is % PROFSTAFF, which measures the number of professional employees as a percentage of the total library staff. The variable was predicted to be positive but is negative for 7 of the 10 years, including the only year to show statistical significance, 1998.
It would appear that the larger the number of professionals, the less likely the positions will be tenure track. This conclusion seems to be counter-intuitive;
one would assume that larger professional staffs would allow for greater labor specialization and ease the burdens on the library of having library professionals pursuing the ‘‘extra’’ duties required by tenure track positions.
But the conclusion is supported by some of the literature discussed above, which indicates that non-research/non-ARL libraries (with smaller profes- sional staffs) may be more likely to support tenure track positions.
Other variables impact the model very little. The regional variables are not statistically significant nor are their signs consistent. There is no reason to believe that there would be a strong regional impact on the probability of tenure, so this was not surprising. The effect of unionization, however, is surprising given the role it played in the OLS model below. In the probit analysis, UNION is consistently negative (as predicted) but is never statistically significant. Based on this study, unionization does not appear to be an important factor when universities choose to offer tenure track options to librarians.
Also consistently negative but not statistically significant was TYPE.
Chressanthis (1994)found public institutions more likely to offer tenure but that supposition is not supported by this study.
The Wage Model
Originally, the author of this study hoped to incorporate a panel study of wage determination, covering the years 1989–1998 into the project. However, preliminary analysis showed no variability in the variable TENURE, making the panel data approach unviable. An alternative model, using cross- sectional data and utilizing OLS regression was thus employed. As shown in Eq. (2), the natural logarithm of starting salaries (LSALARIES) served as the dependent variable and a number of both library- and institution-specific
variables were used to estimate the model for each year (1989–1998). Only the library-specific variables proved to be consistently statistically significant across the 10 years. Tables 10A and 10B report the empirical results for the OLS wage model. The estimated equations all obtained a significant F-statistic and an acceptable cross-sectional adjustedR2.
Surprisingly, the variable of interest, TENURE, proved to be of little importance in the model, regardless of the year. For all 10 years, the sign is positive, which runs counter to the hypothesis that tenure-granting institutions have lower starting salaries. Compensating wage differential theory predicts the effect of tenure to be negative on wages. However, the lack of statistical significance refutes the common alternative argument in the library science literature – namely, the positive impact tenure has on compensation. The results
Table 10A. Model 2: OLS Cross-sectional Regression Estimates by Year: 1989–1993 (Dependent Variable¼LSALARIES,N¼78).
Variable 1989 1990 1991 1992 1993
CONSTANT 9.7799 9.9556 9.958 9.9758 10.0405
(115.477) (126.143) (124.762) (102.396) (115.984)
TENURE 0.0096 0.0112 0.0033 0.0103 0.0088
(0.534) (0.586) (0.184) (0.550) (0.454)
UNION 0.1230 0.0933 0.0987 0.1108 0.0923
(4.565) (3.360) (3.737) (4.049) (3.043)
TYPE 0.0666 0.0586 0.0553 0.0745 0.0637
(2.651) (2.406) (2.250) (2.906) (2.416)
VOLUMES 0.1150E07 0.3760E09 0.6567E09 0.1818E09 0.6490E08
(1.172) (0.050) (0.076) (0.19) (0.679)
% PROFSTAFF 0.1134 0.2816 0.0933 0.1335 0.1256
(0.469) (1.288) (0.380) (0.513) (0.556)
EXPEND 0.2717E07 0.1899E07 0.1871E07 0.2280E07 0.9172E08
(2.659) (2.183) (1.798) (2.198) (0.930)
PHD FIELDS 0.4220E03 0.1793E03 0.1525E03 0.1603E03 0.6033E04
(0.933) (0.370) (0.373) (0.294) (0.115)
URBAN 0.0360 0.0200 0.0169 0.0144 0.0209
(2.004) (1.069) (0.880) (0.715) (0.890)
SOUTH 0.0055 0.0193 0.0029 0.0012 0.0133
(0.195) (0.761) (0.117) (0.046) (0.467)
MIDWEST 0.0082 0.0024 0.0062 0.6988E03 0.0101
(0.265) (0.088) (0.231) (0.024) (0.314)
WEST 0.0778 0.0572 0.0597 0.0736 0.0868
(2.189) (1.683) (2.011) (2.188) (2.527)
F-statistic 6.14 5.41 5.04 6.24 3.86
AdjustedR2 0.4236 0.3864 0.3657 0.4283 0.2901
Note:( ): Absolute value oft-statistic;t-statistics are corrected for heteroscedasticity.
Statistically significant at the .10 level, one-tailed test.
Statistically significant at the .05 level, one-tailed test.
Statistically significant at the .01 level, one-tailed test.
indicate that the existence of TENURE is insignificant in wage formation for academic librarians at ARL institutions, at least at the entry level.
Not so surprisingly, UNION proved to be a more powerful variable in the model. For 9 of the 10 years under study, UNION was statistically significant at either the .05 or the .01 level, using a one-tailed test. UNION was not significant in the last year, which will be discussed below.
The only other consistently significant variable was TYPE. A priori, TYPE was hypothesized to be positive, and the results of the OLS cross- sectional regressions show this to be the case. Private universities are often more heavily endowed, which can substantively increase the financial resources available to the university for salaries.Zoghi (2000)also suggests that public universities are often more constrained in terms of tuition;
Table 10B. Model 2: OLS Cross-sectional Regression Estimates by Year: 1994–1998 (Dependent Variable¼LSALARIES,N¼78).
Variable 1994 1995 1996 1997 1998
CONSTANT 10.1165 10.1700 10.1984 10.3318 10.3547
(126.922) (138.260) (124.777) (153.480) (165.277)
TENURE 0.0130 0.0047 0.0165 0.0019 0.0082
(0.702) (0.259) (0.929) (0.111) (0.433)
UNION 0.0550 0.0635 0.0573 0.0458 0.0237
(1.743) (1.943) (1.737) (1.660) (0.752)
TYPE 0.0485 0.0533 0.0646 0.0523 0.0674
(2.094) (2.184) (2.613) (2.157) (2.462)
VOLUMES 0.9346E08 0.1387E07 0.5012E08 0.1095E07 0.5199E08
(1.060) (1.467) (0.576) (1.448) (0.699)
% PROFSTAFF 0.1165 0.0674 0.2405 0.4353 0.3629
(0.578) (0.344) (1.030) (2.225) (2.114)
EXPEND 0.7360E08 0.2854E08 0.7605E08 0.6363E08 0.2941E08
(0.878) (0.335) (0.927) (1.029) (0.478)
PHD FIELDS 0.3910E03 0.5607E03 0.3543E04 0.8804E03 0.3186E04
(0.754) (1.067) (1.160) (1.821) (1.247)
URBAN 0.0120 0.0058 0.0146 0.0216 0.1923
(0.500) (0.256) (0.660) (1.129) (0.866)
SOUTH 0.1980 0.0156 0.0088 0.0148 0.0254
(0.699) (0.586) (0.291) (0.604) (0.809)
MIDWEST 0.0083 0.0080 0.0085 0.0238 0.0278
(0.261) (0.262) (0.293) (0.924) (0.978)
WEST 0.0321 0.0311 0.0465 0.0267 0.0274
(0.995) (1.015) (1.670) (1.068) (1.046)
F-statistic 2.38 2.51 2.15 3.34 1.89
AdjustedR2 0.1642 0.1778 0.1415 0.2507 0.1130
Note:( ): Absolute value oft-statistic;t-statistics are corrected for heteroscedasticity.
Statistically significant at the .10 level, one-tailed test.
Statistically significant at the .05 level, one-tailed test.
Statistically significant at the .01 level, one-tailed test.
private universities can more freely raise tuition, which enhances their ability to offer higher salaries. The present study is consistent with this assumption.
Other library-specific variables included VOLUMES, % PROFSTAFF, and EXPEND. All three were significant in at least one of the years but lack any consistency as to either the sign or statistical significance. The assumption that larger libraries, either in terms of staffing (% PROFSTAFF) or VOLUMES, offer higher salaries does not appear to be substantiated by the results.
EXPEND was statistically significant for the early years of 1989–1992 but not for the later years. This may reflect the changing labor market for academic librarians. Due to an apparent labor shortage, many academic libraries are finding it difficult to recruit and retain qualified librarians (Raschke, 2003). If a shortage of librarians persisted throughout the sample period, then wages should be observed to continually rise. Also, jobs should be readily available.
This would lesson the need for tenure at least in terms of the job security commonly associated with tenure. Should a job loss occur, the costs of unemployment is less during periods of labor shortage and rising wages.
Other than TYPE, few of the institution-specific variables proved to be statistically significant in the study. For 1997 and 1998, PHD FIELDS was statistically significant but the signs were not stable. PHD FIELDS had been hypothesized to be positive, but was negative for 4 of the 10 years.
No a priori assumption was made concerning the sign of URBAN. For the first six years of the study, it was negative, reflecting a negative relationship between higher starting salaries and urban locations. This may be the result of rural institutions having to offer a positive differential to offset the lack of amenities and job opportunities for spouses and families. Beginning with 1995, however, the sign becomes positive. For 1995–1998, URBAN is positive but lacks statistical significance. This may be a function of the data collected or it may reflect reduced funding to state-supported rural universities.
Of the regional variables, only WEST showed some consistent results in terms of both the sign and statistical significance. The expected signs for the regional variables had been indeterminate prior to the analysis. SOUTH was usually negative, perhaps reflecting lower regional salaries, but the lack of statistical significance makes any conclusions tenuous. MIDWEST was negative for 6 of the 10 years but again lacks any statistical significance.
WEST, however, was consistently positive and statistically significant for 6 of the 10 years, including 1989–1993 and 1996. The lack of statistical significance in the latter period of the study, as well as the decrease in the magnitude of the estimate, may be the result of funding difficulties experienced by higher educational systems located in the West, especially in the state of California (Lively, 1992).
The last year of the study deserves additional discussion. The results for 1998 are markedly different than the first nine years. Variables that were consistently significant in the other years are not in 1998 – such as UNION and WEST. Only two variables are found to be statistically significant, TYPE and PHD FIELDS. The overall adjusted R2 for the model is a modest 11%, substantively lower than the 42% in 1989. Whether this variability in the data for 1998 is a function of the data collection method or an indication of a deeper, underlying trend is beyond the analysis of this study. Additional date for the post-1998 period is needed to address this apparent break in the trend.
OLS regression requires a number of conditions. One of those conditions is that no independent variable be a linear function of one or more other independent variables. Multicollinearity occurs when this condition is not met. Economic data often exhibit some degree of multicollinearity and one of a number of diagnostics is recommended when examining regression data (Studenmund & Cassidy, 1987). One method for examining possible multicollinear variables is to examine the Pearson correlation matrix. The year 1994 was selected as a representative year of the sample and its data were used for further diagnostic examination.Tables 11A and 11B report the Pearson correlation statistics for 1994. An analysis of the Pearson correlation statistics reveals only two variables with a relatively high degree of correlation: EXPEND and VOLUMES. Given the nature of these two variables, some degree of correlation is to be expected and is not cause for removal from the model.
Another diagnostic of multicollinear data is the Variance Inflation Factors or VIFs. VIFs are an indicator of the effect that the other predicator variables have on the variance of a regression coefficient directly
Table 11A. Pearson Correlation Coefficients, 1994.
TENURE UNION TYPE VOLUMES %
PROFSTAFF
EXPEND
TENURE 1.000 0.009 0.292 0.237 0.124 0.149
UNION 0.009 1.000 0.322 0.114 0.240 0.004
TYPE 0.29251 0.322 1.000 0.120 0.339 0.044
VOLUMES 0.23739 0.114 0.120 1.000 0.002 0.865
% PROFSTAFF 0.124 0.240 0.339 0.002 1.000 0.100
EXPEND 0.149 0.004 0.044 0.865 0.100 1.000
PHD FIELDS 0.050 0.099 0.161 0.388 0.043 0.398
URBAN 0.075 0.235 0.041 0.104 0.195 0.047
SOUTH 0.025 0.299 0.000 0.222 0.144 0.196
MIDWEST 0.075 0.112 0.103 0.083 0.025 0.007
WEST 0.036 0.300 0.241 0.047 0.249 0.057
related to the tolerance value (Hair et al., 1995). According to Hair et al.
(1995, p. 127), each researcher must set his/her own threshold, but a common cutoff threshold is a VIF equal to 10. Table 12reports the VIFs for the year 1994. Again, only EXPEND and VOLUMES show fairly high VIFs, with values in excess of 4. However, an analysis of the model with and without one or both variables does not yield substantively different results in either the overall predictive capability of the model or in the statistical significance of the individual regressors. Given the theoretical importance of these two variables, as proxies for institutional support for the library and the total library collection size, the decision was made to keep them in the model.
Table 11B. Pearson Correlation Coefficients, 1994.
PHD FIELDS URBAN SOUTH MIDWEST WEST
TENURE 0.050 0.075 0.025 0.075 0.036
UNION 0.099 0.235 0.299 0.112 0.300
TYPE 0.161 0.041 0.000 0.103 0.241
VOLUMES 0.388 0.104 0.222 0.083 0.047
% PROFSTAFF 0.043 0.195 0.144 0.025 0.249
EXPEND 0.398 0.047 0.196 0.007 0.057
PHD FIELDS 1.000 0.084 0.152 0.191 0.012
URBAN 0.084 1.000 0.073 0.075 0.045
SOUTH 0.152 0.073 1.000 0.391 0.351
MIDWEST 0.191 0.075 0.391 1.000 0.310
WEST 0.012 0.045 0.351 0.310 1.000
Table 12. Variance Inflation Factors, 1994.
TENURE 1.2158
UNION 1.5975
TYPE 1.6707
VOLUMES 4.9145
% PROFSTAFF 1.2553
EXPEND 4.5734
PHD FIELDS 1.3427
URBAN 1.1187
SOUTH 2.3425
MIDWEST 2.0034
WEST 1.9467
An Alternative Test
The analysis above assumes that there is no underlying distinction between the librarian labor markets in tenure track versus non-tenure track ARL libraries. In other words, there is no direct evidence of labor market segmentation occurring. But is this conclusion warranted?
A separate analysis of the data examined wage determination across tenure track and non-tenure track ARL libraries. Tables 13A–13E report separate wage equations for the tenure- and non-tenure-granting
Table 13A. Wage Equations: Tenured versus Non-tenured ARL Libraries, 1989–1990.
1989 1990
Non-tenured Tenured Non-tenured Tenured
CONSTANT 9.8863 9.5760 10.0501 9.7076
(93.147) (62.382) (94.119) (61.515)
UNION 0.1344 0.0822 0.1041 0.0823
(2.977) (1.703) (2.482) (1.822)
TYPE 0.0603 0.0422 0.0251 0.0361
(1.763) (0.870) (0.822) (0.769)
VOLUMES 0.5984E08 0.1187E07 0.2013E08 0.1379E08
(0.332) (0.570) (0.149) (0.068)
% PROFSTAFF 0.1952 1.0993 0.4395 0.8535
(0.610) (1.943) (1.477) (1.353)
EXPEND 0.2544E07 0.2794E07 0.2363E07 0.8132E08
(1.212) (1.264) (1.587) (0.432)
PHD FIELDS 0.3039E03 0.6823E03 0.0010 0.0013
(0.463) (1.002) (1.772) (1.861)
URBAN 0.0382 0.0668 0.0240 0.0557
(1.264) (1.614) (0.909) (1.483)
SOUTH 0.0120 0.0518 0.0089 0.0725
(0.283) (0.972) (0.227) (1.395)
MIDWEST 0.0210 0.0754 0.2465 0.0348
(0.508) (0.143) (0.648) (0.697)
WEST 0.0812 0.0482 0.4190 0.0412
(1.669) (0.871) (0.961) (0.793)
N 44 34 44 34
F-statistic 5.19 2.36 5.54 2.30
AdjustedR2 0.4936 0.2919 0.5138 0.2822
Note:( ): Absolute value oft-statistic.