unionization and faculty salaries: new evidence from the 1990s
TRANSCRIPT
Unionization and Faculty Salaries" New Evidence from the 1990s
JAMES M O N K S
Mount Holyoke College, South Hadley, MA 01075
The literature on how unionization affects faculty salaries and compensation is incon- clusive. I use the 1993 National Survey of Postsecondary Faculty to investigate how col- lective bargaining affects faculty salaries. Union representation significantly alters the returns to individual and institutional characteristics, and unionized faculty receive a premium of between 7 and 14 percent, an earnings differential that is substantially larger than those found in most earlier studies.
I. Introduction
The National Labor Relations Board recently changed an 18-year ruling that college and university professors had sufficient influence over institution governance to be considered managerial employee and were thus ineligible to bargain under the National Labor Rela- tions Act. This reversal opens the door for increased union representation and collective bargaining at private colleges and universities and warrants further investigation into the pecuniary returns to unionization. I investigate the effect of union representation on fac- ulty salaries using individual-level data from the 1993 National Survey of Postsec- ondary Faculty (NSOPF) and find a union premium which is larger than most existing studies and robust to various specifications and estimation techniques. In particular, unionized faculty earn approximately 7 to 14 percent more than nonunion faculty.
A number of studies have examined the influence of unionization and collective bargaining on faculty salaries and compensation at American colleges and universities. There is, however, no consensus regarding how unions affect faculty salaries. One group of studies (Birnbaum, 1974, 1976; Morgan and Kearny, 1977; Leslie and Hu, 1977) found that unionization positively affects faculty salaries, while others (Marshall, 1979; Guthrie-Morse et al., 1981; Hu and Leslie, 1982; Kesselring, 1991; Rees, 1993) found either that unions had no significant impact on faculty salaries or in some cases a neg- ative impact. All of these studies use data from the American Association of University Professors' (AAUP)Annual Survey of Faculty Compensation. Unfortunately, these sur- veys only report the mean salary by rank at each institution.
Only four studies to my knowledge use individual-level data to examine how unionization affects faculty salaries. Ashraf (1992) and Barbezat (1989) use data from the 1977 Survey of the American Professoriate. Both the Ashraf and Barbezat studies
J O U R N A L OF LABOR R E S E A R C H
Volume XXI, Number 2 Spring 2000
306 JOURNAL OF LABOR RESEARCH
find that unionization has a positive and significant impact on faculty salaries. Barbezat finds a 2 percent union premium on average, while Ashraf estimates a 4 percent over- all union effect that varies substantially by faculty sub-group. Two more recent studies by Ashraf (1997, forthcoming) also use data from the 1988 and 1993 National Survey of Postsecondary Faculty. Ashraf finds limited evidence of a union effect in the 1988 data, and significant variation in the union premium across institutional type in the more recent data set.
My data set is superior to the 1977 Survey of the American Professoriate used by Ashraf and Barbezat in a number of ways. First, it is newer. The NSOPF contains fac- ulty and institutional information for the 1992-1993 academic year. Second, it covers a larger number of faculty and institutions. The NSOPF is a survey of 25,780 faculty at 817 institutions. For example, Barbezat's final sample consists of 3,404 individuals at 158 institutions, and only 33 of these institutions are unionized. In contrast, my final sample contains 8,198 individuals across 734 institutions, and 254 of these institutions have unionized faculty. Ashraf's sample of faculty from the 1993 NSOPF is much larger than my sample. His sample selection and estimation techniques do not appear to prop- erly account for the large representation of part-time, temporary, research, and ad- ministrative faculty in the survey. Nor does he control for over-sampling by field of specialization, and the widespread use of imputed values for missing values. Addi- tionally, it is unclear how union representation is measured in Ashraf's studies. The sample used in this paper contains only full-time teaching faculty who provide valid answers to each of the survey questions used in this analysis. Furthermore, the union indicator variable reflects union representation of full-time instructional faculty, the sample of faculty used in this analysis.
II. Data
The NSOPF was conducted by the National Opinion Research Center (NORC) to pro- vide a national profile of faculty at public and private, two- and four-year nonpropri- etary institutions. Surveys were sent to both faculty and an administrative office at each of the selected institutions. The survey received valid responses from 25,780 individu- als at 817 tertiary institutions. My sample excluded those who are not full-time, regu- lar faculty (9,847); whose primary activity is not teaching (4,215); who did not report their highest degree received (70); had basic salary less than $1,000, greater than $300,000, or had salary unreported (979); who did not report one or more of the other explanatory variables used in the regressions (1,704); or their institution did not report whether their faculty are represented by a union (767). This leaves 8,198 individuals at 734 institutions.
One of the questions posed in the institutional survey was whether "any of your full-time instructional faculty/staff [are] legally represented by a union (or other asso- ciation) for purposes of collective bargaining with the institution. ''1 Table 1 presents selected variable means by union representation. Note that faculty represented by unions earn on average over $3,000 more than their nonunion counterparts. In addi-
JAMES MONKS 307
Table 1
Variable Means by Union Representation
Nonunion Union
Persons 5,552 2,646
Individual Characteristics Basic Salary 39,517 43,127"** Experience 15.07 16.58 * * * Seniority 11.11 12.94*** Male 0.59 0.58 Black 0.09 0.07** Hispanic 0.04 0.05** Asian 0.05 0.05 Native American 0.01 0.01
Rank Assistant Professor 0.27 0.19"** Associate Professor 0.23 0.22 Full Professor 0.26 0.29**
Public Control 0.62 0.94***
Carnegie Classification Two-Year College 0.23 0.51 *** Liberal Arts College 0.14 0.01 *** Comprehensive College 0.31 0.36*** Doctoral University 0.16 0.06*** Research University 0.10 0.04*** Specialized Institution 0.06 0.02***
Primary Field of Teaching Fine Arts 0.08 0.07 Business and Communications 0. I 0 0.11 * * Computer Science 0.03 0.03 Education 0.08 0.08 Engineering 0.04 0.03*** Modern Languages 0.14 0.15 Health 0.10 0.10 Natural Sciences O. 10 0.09** Mathematics 0.06 0.06 Social Sciences 0.11 0.12 Other 0.16 0.16
Career Publication Productivity Refereed Journal Articles 6.05 4.46*** Non-refereed Journal Articles 5.78 6.12 Book Reviews 2.87 2.13*** Book Chapters 0.87 0.66*** Books 0.57 0.47** Manuscripts 4.07 3.70 Presentations 27.15 22.85* Software and Products 0.50 0.54
Institutions 480 254
Public Control 0.58 0.93***
Carnegie Classification Two-Year College 0.24 0.58*** Liberal Arts College 0.12 0.01 * * * Comprehensive College 0.26 0.26 Doctoral University 0.15 0.06* ** Research University 0.13 0.06*** Specialized Institution 0.10 0.02***
Notes: *** (**,*) indicates significantly different from the nonunion variable at the 1% (5%,10%) level; two-tailed test.
308 JOURNAL OF LABOR RESEARCH
tion, it appears a much larger percentage of those covered by union representation are unranked, that is, they are more likely to be visiting, instructors, or lecturers than an assistant, associate, or full professor. Institutions faced with union representation may attempt to cover higher labor costs by using more non-tenure-track employees. This is, however, suggestive - - a full examination of this hypothesis is beyond the scope of this study.
Unionized faculty also have higher average levels of experience and seniority and are much more likely to be at two-year colleges and public institutions. Over 50 per- cent of the unionized faculty in this survey are at a two-year college, and 94 percent are at a public institution. Additionally, 58 percent of unionized institutions are two-year colleges, and 93 percent of unionized institutions are publicly controlled. Union rep- resentation is clearly not randomly allocated across institutional type, and individuals may self-select into union-represented institutions. Care must be taken to control for institutional characteristics and possible individual self-selection in examining the impact of unions on faculty salaries. 2
III. Empirical Results Several regression analyses were performed to assess how union representation affects faculty salaries conditional on numerous individual and institutional characteristics. Specification (I) of Table 2 begins this discussion by presenting the results of a regres- sion of the log of basic salary on experience (years since highest degree) and its square, seniority (years at current institution) and its square, dummy variables for gender, race, rank, the institution's Carnegie classification, control of the institution, primary field of teaching, and a dummy variable indicating whether the individual is employed at an institution where full-time instructional faculty are represented by a union. 3 (Also included among the regressors but not shown are dummy variables for highest degree received, length of contract in months, and region.) The omitted category is white, female, unranked, at a private, comprehensive institution, in a social science field. I find concave returns to experience and seniority and that males and Asians earn sig- nificantly more than white females. I also find that unionized faculty earn 7.3 percent more than nonunion faculty.
There is some evidence (Barbezat, 1989) that unions replace merit in the com- pensation structure. As an additional specification I control for career publication pro- ductivity by including the individual faculty member's number of refereed journal articles, non-refereed journal articles, book reviews, book chapters, books, manuscripts and reports, presentations, and software and other products. While both the number of refereed journal articles and book chapters positively and significantly affect earnings, inclusion of publication productivity does not alter the union premium. Even with these additional measures of merit, union represented employees earn over 7 percent more than their counterparts at comparable nonunion institutions.
The regression analyses of Table 2 do not allow for interaction of the union term with the other explanatory variables. Union representation may significantly alter the
Tab
le 2
. U
nion
Rep
rese
ntat
ion
and
Fac
ulty
Sal
arie
s (D
epen
dent
Var
iabl
e: L
og
of
Bas
ic S
alar
y)
Var
iabl
e N
ame
( 1 )
(2)
Var
iabl
e N
ame
(I)
(2)
Var
iabl
e N
ame
(1)
(2)
Inte
rcep
t 9.
69**
* 9.
69**
* C
arne
gie
Cla
ssif
icat
ion
Nat
ural
Sci
ence
s
(0.0
36)
(0,9
36)
Res
earc
h U
nive
rsity
0.
145"
**
0.11
5"**
R
epre
sent
ed b
y a
Uni
on
0.07
3***
0.
073*
**
(0.0
14)
(0.0
15)
Mat
h
(0.0
10)
(0.9
10)
Doc
tora
l U
nive
rsity
0.
079*
**
0.06
2***
E
xper
ienc
e 0.
008 *
* *
0.00
8 * *
* (0
.012
) (0
.012
) O
ther
Fie
ld
(0.0
014)
(0
.001
4)
Lib
eral
Art
s C
olle
ge
-0.0
62**
* -0
.060
***
Exp
erie
nce
Squa
red
-0.0
001
-0.0
001
* (0
.015
) (0
.015
) C
aree
r P
ubli
cati
ons
(0,0
000)
(0
.000
0)
Two-
Year
Col
lege
0.
004
0.00
8 R
efer
eedJ
ourn
alA
rtic
les
Seni
orit
y 0.
010"
**
0.01
0***
(0
.011
) (0
.011
)
(0.0
014)
(0
.001
4)
Spec
iali
zedl
nsti
tuti
on
0.06
1"**
0.
054*
**
Non
-ref
eree
dJou
rnal
Art
icle
s Se
ninr
ity
Squa
red
-0.0
001
~**
-0.0
001
**
(0.0
20)
(0.0
20)
(0.0
000)
(0
.000
0)
Pub
lic' I
nstit
utio
n -0
.005
-0
.003
B
ook
Rev
iew
s M
ale
0.04
9***
0.
047*
**
(0.0
10)
(0.0
11 )
(0.0
08)
(0.0
08)
Pri
mar
y F
ield
of
Teac
hing
B
ook
Cha
pter
s B
lack
0,
012
0.01
4 F
ine
Art
s 4)
.012
0,
003
(0.0
13)
(0.0
13)
(0.0
17)
(0.0
17)
Boo
ks
His
pani
c 0.
002
-0.0
02
Bus
ines
s an
d C
omm
unic
atio
n 0.
104"
**
0,10
8"**
(0
.018
1 (0
.018
) (0
.015
) (0
,015
) M
anus
crip
ts a
nd R
epor
ts
Asi
an
0.02
9*
0.02
6 (0
.017
) (0
,017
) C
ompu
ter
Scie
nce
0.07
1"**
0.
072*
**
(0.0
25)
(0.0
25)
Pre
sent
atio
ns
Nat
ive
Am
eric
an
-0.0
36
-0.0
36
Edu
cati
on
-0,0
16
-0.0
10
(0,0
48)
(0.0
48)
(0.0
17)
(0.0
17 )
Soft
war
e an
d P
rodu
cts
Ass
ista
nt P
rofe
ssor
0.
048*
**
0.05
3***
(0
.012
) (0
,012
) E
ngin
eeri
ng
0.11
0"**
0.
110"
**
(0.0
21 )
(0
.022
) A
ssoc
iate
Pro
fess
or
0.11
5"**
0.
115"
**
(0.0
12)
(0.0
12)
Mod
ern
Lang
uage
s -0
,046
"**
-0.0
41"*
* ad
just
ed R
-squ
ared
0.
38
(0,0
14)
(0,0
14)
Nm
nber
of
Obs
erva
tion
s 8,
198
Ful
l Prq
fess
or
0.22
5***
0.
209*
**
Hea
lth
0 10
0"**
0,
099*
**
(0.0
13)
(0.0
13)
(0.0
16)
(0.0
16)
-0.0
22
-0,0
24
(O.O
l 5)
(0.0
16)
0.02
2 0.
028
(0.0
18)
(0.0
1 g)
0.00
6 0.
008
(0,0
14)
(0.0
14)
0.00
1"**
(0
.000
3)
-0.0
000
(0.0
001)
-0.0
000
(0.0
003)
0.00
7***
(0
,001
6)
0.00
3 (0
.002
3)
0.00
03
(0.0
002)
-0.0
000
(0.0
000)
0.00
07
(0.0
01 l
)
0.39
0 Z
Not
es:
Stan
dard
err
ors
in p
aren
thes
es.
***
(**,
*) i
ndic
ates
sig
nifi
cant
ly d
iffe
rent
fro
m z
ero
at t
he 1
% (
5%,1
0%)
leve
l. In
clud
ed a
mon
g th
e re
gres
sors
but
not
sho
wn
are
dum
my
vari
able
s t.~
fo
r hi
ghes
t deg
ree
rece
ived
(pr
oles
sion
al d
egre
e an
d Ph
.D.)
, le
ngth
of
cont
ract
in m
onth
s, a
nd r
egio
n.
,,~
ta3
Tab
le 3
. U
nion
Rep
rese
ntat
ion
and
Fac
ulty
Sal
arie
s
(Dep
ende
nt V
aria
ble:
Log
of
Bas
ic S
alar
y)
Var
iabl
e N
ame
Uni
on
Uni
on
Non
-Uni
on
Non
-Uni
on
Inte
rcep
t 9.
79**
* 9.
88**
* 9.
60**
* 9.
62**
* (0
.070
) (0
.012
) (0
,044
) (0
.046
)
Exp
erie
nce
0.00
7***
0.
007*
**
0,00
8***
0,
008*
**
(0.0
023)
(0
.002
3)
(0.0
017)
(0
.001
7)
Exp
erie
nce
Squa
red
-0.0
001
-0.0
001
-0.0
001
-0.0
001
(0.0
001)
(0
.000
1)
(0.0
000)
(0
.000
0)
Seni
orit
y 0.
016"
**
0.01
6"**
0.
006*
**
0.00
6***
(0
.002
2)
(0.0
022)
(0
.001
9)
(0.0
019)
Seni
orit
y Sq
uare
d -0
.000
2***
-0
.000
2***
-0
.000
1 -0
.000
1 (0
.000
1)
(0.0
001)
(0
.000
1)
(0.0
001)
Mal
e 0.
031"
* 0.
031"
* 0.
047*
**
0.04
7***
(0
.014
) (0
.014
) (0
.010
) (0
.010
)
Bla
ck
0.01
6 0.
014
0.00
8 0.
008
(0.0
24)
(0.0
24)
(0.0
t6)
(0.0
16)
His
pani
c -0
.005
-0
.010
0.
005
0.00
6 (0
.028
) (0
.029
) (0
.022
) (0
.022
)
Asi
an
0.02
5 0.
023
0.02
5 0.
025
(0.0
28)
(0.0
28)
(0.0
21)
(0.0
21)
Nat
ive
Am
eric
an
0.06
4 0.
063
-0.0
93
-0.0
94
(0.0
77)
(0.0
77)
(0.0
60)
(0.0
60)
Ass
ista
nt P
rofe
ssor
-0
.004
0.
003
0.08
7***
0.
088*
**
(0.0
21)
(0.0
22)
(0.0
14)
(0.0
14)
Ass
ocia
te P
rofe
ssor
0.
066*
**
0.06
8***
0.
159"
**
0.16
2"**
(0
.020
) (0
.020
) (0
.016
) (0
.016
)
Var
iabl
e N
ame
Uni
on
Uni
on
Non
-Uni
on
Non
-Uni
on
Pub
lic
Inst
itutio
n 0.
069*
* -0
.015
0.
001
0.01
7 (0
.029
) (0
.097
) (0
,012
) (0
.016
)
Pri
mar
y F
ield
of
Teac
hing
Fin
e A
rts
0.02
9 0.
029
0.00
1 0.
001
(0.0
30)
(0.0
30)
(0.0
21 )
(0.0
21 )
Bus
ines
s an
d C
omm
unic
atio
ns
0.06
1"*
0.06
0**
0.13
6"**
0.
136"
**
(0.0
26)
(0.0
26)
(0.0
19)
(0.0
19)
Com
pute
r Sc
ienc
e 0.
039
0.04
7 0.
097*
**
0.09
3***
(0
.041
) (0
.042
) (0
.030
) (0
.030
)
Edu
catio
n 0.
012
0.01
9 -0
.025
-0
.026
(0
.028
) (0
.029
) (0
.020
) (0
.020
)
Eng
inee
ring
0.
094*
* 0.
110"
* 0.
118"
**
0.11
3"**
(0
.040
) (0
.044
) (0
.026
) (0
.026
)
Mod
ern
Lang
uage
s -0
.038
-0
.032
-0
.042
***
-0,0
44**
(0
.024
) (0
.025
) (0
.017
) (0
.017
)
Hea
lth
0.08
2***
0.
089*
**
0.10
1"**
0.
099*
**
(0.0
28)
(0.0
29)
(0.0
20)
(0.0
20)
Nat
ural
Sci
ence
s -0
.025
-0
.014
-0
.023
-0
.025
(0
.027
) (0
.030
) (0
.019
) (0
.019
)
Mat
h 0.
035
0.04
3 0.
032
0.03
0 (0
.031
) (0
.032
) (0
.022
) (0
.022
)
Oth
er F
ield
0.
033
0.03
6 -0
.002
-0
.002
(0
.023
) (0
.024
) (0
.017
) (0
.017
)
> 0 > 0 Ed >
Ful
l P
rofe
ssor
0.
137"
**
0.14
2"**
0.
271"
**
0.27
3***
(0
.020
) (0
.021
) (0
.018
) (0
.018
)
Car
negi
e C
lass
ifica
tion
Res
earc
h U
nive
rsit
y 0.
087*
**
0.12
1"**
0.
112"
**
0.10
5"**
(0
.032
) (0
.049
) (0
.017
) (0
.017
)
Doc
tora
l U
nive
rsit
y 0.
005
0.03
1 0.
065*
**
0.06
0***
(0
.027
) (0
.040
) (0
.014
) (0
.014
)
Lib
eral
Art
s C
olle
ge
4).1
54"*
* 4)
.113
4)
.056
***
4).0
59**
* (0
.072
) (0
.085
) (0
.016
) (0
.016
)
Two-
Year
Col
lege
4)
.034
* 4)
.040
**
0.00
3 0.
006
(0.0
18)
(0.0
19)
(0.0
15)
(0.0
15)
Spec
iali
zed
Inst
itutio
n 0.
114"
* 0.
146"
* 0.
040*
0.
035
(0.0
51 )
(0.0
62)
(0.0
21 )
(0
.022
)
Inve
rse
Mil
ls R
atio
0.
074
-0.0
33
(0.0
82)
(0.0
22)
adju
sted
R-s
quar
ed
0.33
0.
33
0.41
0.
41
No.
of
Obs
erva
tion
s 26
46
2646
55
52
5552
Car
eer
Pub
lica
tion
s
Ref
eree
d Jo
urna
l A
rtic
les
O.O
00g*
0.
0007
0.
0018
"**
0.00
18"*
* (0
.000
4)
(0.0
005)
(0
.000
3)
(0.0
003)
Non
-ref
eree
d Jo
urna
l A
rtic
les
0.00
00
0.00
00
4).0
001
4).0
001
(0.0
002)
(0
.000
2)
(0.0
002)
(0
.000
2)
Boo
k R
evie
ws
~).0
007
~0.0
006
4).0
002
0.00
02
(0.0
006)
(0
.000
6)
(0.0
004)
(0
.000
4)
Boo
k C
hapt
ers
0.00
7**
0.00
7**
0.00
7***
0.
008*
**
(0.0
029)
(0
.003
0)
(0.0
019)
(0
.001
9)
Boo
ks
0.00
5 0.
006
0.00
1 0.
001
(0.0
043)
(0
.004
3)
(0.0
026)
(0
.002
6)
Man
uscr
ipts
and
Rep
orts
0.
0002
0.
0003
0.
0003
0.
0003
(0
.000
4)
(0.0
004)
(0
.000
2)
(0.0
002)
Pre
sent
atio
ns
0.00
01
0.00
0 l
4).0
001
4).0
001
(0.0
00 l )
(0
.000
1 )
(0.0
000)
(0
.000
0)
Soft
war
e an
d P
rodu
cts
0.00
25
0.00
24
4).0
000
0.00
00
(0.0
017)
(0
.001
8)
(0.0
014)
(0
.001
4)
Cho
w T
est
4.80
***
Not
es:
See
note
s to
Tab
le 2
.
0 Z
312 JOURNAL OF LABOR RESEARCH
returns to various individual measures of human capital and job type. To allow for this possibility in the least restrictive manner I perform separate regression analyses for union and nonunion faculty. Table 3 presents these results.
The first column of Table 3 presents the results for unionized employees using the full complement of regressors. There are significant differences in the returns to a num- ber of individual attributes across union representation. The Chow test that the coeffi- cients are the same across union representation is rejected at the 1 percent significance level. In particular, seniority has a strong effect on earnings in the union sector. The coefficient on seniority is 0.016 for union faculty and only 0.006 for nonunion faculty. On the other hand, the returns to being an assistant, associate, or full professor are larger in the nonunion sector. There is less dispersion of earnings across fields in the union sector, and a greater return to refereed journal articles in the nonunion sector, as expected. There is also a larger gender gap in earnings in the nonunion sector, with males earning 3 percent more than females in the union sector and 4.7 percent more in the nonunion sector. These results are consistent with Barbezat's (1989) among the fac- ulty surveyed in 1977.
As an alternative specification, I control for possible self-selection among faculty into jobs at union and nonunion institutions. If individuals chose between union and nonunion jobs in order to maximize their earnings based on unobservable characteris- tics, then OLS estimation may result in biased estimates of the returns to union repre- sentation. I correct for this source of bias by using the now-familiar Heckman (1979) two-step probit selection correction method. I include among the regressors in the selec- tion equation the full set of regressors from the earnings equation and the individual's marital status and number of children. 4 The inverse of the Mills ratio is then included among the regressors in the earnings equations. The estimated coefficients in both the union and nonunion earnings equations are robust to this selection correction, and the coefficients on the inverse Mills ratios are insignificantly different from zero.
Following the approach of Duncan and Leigh (1985) and Kesselring (1991), using the estimated coefficients from the selectivity corrected regressions, I calculate a pre- dicted log salary for each individual in both the union and nonunion sector. These pre- dicted log values are then converted to basic salary and a union earnings differential is constructed for each individual. 5 The estimated average union earnings premium is approximately 14 percent. 6 In other words, unionized faculty earn approximately 14 percent more than comparable nonunion faculty.
IV. Conclusion
The existing literature on the returns to union representation among academic faculty is inconclusive. Some studies have found significant returns to collective bargaining, while others have concluded that union representation has little or no effect. Existing studies using individual-level data from 1977 find a statistically significant positive impact of union representation on faculty salaries of between 2 and 4 percent; more recent studies find mixed evidence of a significant union affect on earnings. Using a
JAMES MONKS 313
more recent and broader survey of faculty across a larger number of institutions, and
careful ly control l ing for individual characterist ics, miss ing data, and self-select ion, I
find much higher returns to union representat ion among academic faculty - - col lec t ive
bargaining raises salaries by approximate ly 7 to 14 percent. Because union represen-
tation is much more l ikely at public and two-year institutions, caut ion must be used in
drawing inferences across insti tutional types based on the aggregate union p r emium
found in this study.
In l ight of the recent N L R B ruling that faculty at private institutions are now eli-
gible to bargain under the N L R A , this finding of substantial returns to union represen-
tation is s ignificant . O f course, my union p r e m i u m appl ies pr imar i ly to publ ic
institutions and does not imply that this same p remium will necessari ly hold for private
institutions. There is also ev idence (Ashraf, 1998, for thcoming) that there is substan-
tial variat ion in the union earnings p remium across individual and insti tutional charac-
teristics. The results of this paper do suggest, however, that the rather minor average
union earnings differentials found in earl ier studies may understate the true impact of
col lec t ive bargaining on current faculty remunerat ion.
N O T E S
IFor institutions indicating that their faculty are represented by a union for purposes of collective bargain- ing, the survey also asked the "approximate percentage of the full time instructional faculty/staff represented by a union." For institutions covered by collective bargaining, the average percentage of full-time instructional faculty/staff represented by a union was over 94 percent.
2The following regression analyses were also performed using sample faculty weights to control for poten- tial bias from oversampling of individuals based on gender, race, and primary field of teaching. The regres- sion results are qualitatively the same.
3A dummy variable for whether the individual reported being a member of the union was also included, but this proved to be insignificant since such an extremely high percentage of the faculty are covered by collec- tive bargaining where union representation occurs and so was excluded from the regressors.
4The results of the selection equation are not shown, but are available from the author on request.
5Ashraf (forthcoming) follows the approach of Cotton (1988) in estimating the union premium. These approaches are conceptually different and, coupled with the differences in sample and variation in the union premium across institutional type outlined in the paper, render strict comparison of our results inadvisable.
6The 14 percent union earnings differential is found using both the selectivity and non-selectivity-corrected estimated coefficients.
R E F E R E N C E S
Ashraf, Javed. "Do Unions Affect Faculty Salaries?" Economics of Education Review ! 1 (Fall 1992): 219- 23,
. "The Effect of Unions on Professors' Salaries: The Evidence over Twenty Years." Journal of Labor Research 3 (Summer 1997): 439-50.
"Collective Bargaining and Compensation at Public Junior Colleges" Journal of Collective Nego- tiations in the Public Sector (forthcoming).
314 JOURNAL OF LABOR RESEARCH
Barbezat, Debra A. "The Effect of Collective Bargaining on Salaries in Higher Education." Industrial and Labor Relations Review 42 (April 1989): 443-55.
Bimbaum, Robert. "Unionization and Faculty Compensation." Educational Record 55 (Winter 1974): 29-33.
. "Unionization and Faculty Compensation: Part II." Educational Record 57 (Spring 1976): 116-18.
Duncan, George M. and Duane E. Leigh. "The Endogeneity of Union Status: An Empirical Test." Journal of Labor Economics 3 (Summer 1995): 385-402.
Gutl~ie-Morse, Barbara, Larry Leslie, and Teh-Wei Hu. "Assessing the Impact of Faculty Unions: The Finan- cial Impact of Collective Bargaining." Journal of Higher Education 52 (May/June 1981): 237-55.
Heckman, James. "Sample Selection Bias As a Specification Error." In Female Labor Supply: Theory and Estimation, J.P. Smith, ed. Princeton, N.J.: Princeton University Press, 1979.
Hu, Teh-Wei and Larry L. Leslie. "The Effects of Collective Bargaining on College Faculty Salaries and Compensation." Applied Economics 14 (June 1982): 269-77.
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Morgan, David and Richard Kearny. "Collective Bargaining and Faculty Compensation: A Comparative Analysis." Sociology and Education 50 (January 1977): 28-39.
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