|
|
Appendix A: The Evaluation Model and Estimated Equations
In non-experimental program designs, selection bias is a major
concern to the evaluator. Without any formal empirical tests, a critic may
refuse to accept the findings from descriptive statistics and multivariate
statistical methods that ignore the selection bias issue. For
example, if, in the absence of the Project, program participants are more
motivated to accept small weeks of work than comparison group
members, then selection bias exists. Under such circumstances,
estimates from econometric estimates without accounting for the influences of selection
bias could be misleading, because the effects of selection bias on
program outcomes have not been purged.
The standard econometric method that deals with selection bias explicitly,
is the Heckman selection bias model. In a nutshell, the model
estimates the influences of the intangibles (e.g., motivation) and tangibles
(personal attributes, socio-economic factors, regional economic climates,
etc.) on program participation and program outcomes. In a typical selection
bias model, the evaluator has to consider the existence of two possible
sources of selection biases, namely administrative bias and self-selection
bias. Administrative bias refers to the cases in which program
administrative officers tend to grant program participation to individuals who
are most likely to succeed only. Since the Small Weeks Pilot Project has been
available to all labour force members in the designated 31 Small Weeks
regions, administrative bias is by definition a non-issue. However, self-selection
remains an outstanding concern. For this investigation, the evaluation
model consists of one participation equation and two outcome equations (small
weeks of work and total weeks of work in the Rate Calculation
Period [RCP]). The model deals with
the issue directly in the participation equation. If program participants were
more motivated to accept small weeks of work than comparison group
members, then this intangible factor would be reflected in the estimated
coefficients of the participation equation. This estimated participation
equation could in turn be used to generate the necessary information for
estimating the two outcome equations.30 The estimated outcomes by
this method are technically and conceptually free of the confounding effects
of selection bias.31
To test the selection bias hypothesis and to see whether or not selection
bias exists in the small weeks data, we have used the
econometric method proposed by Heckman, along with the data from 31 Small
Weeks Pilot Project regions and the rest of the economy,32 to
estimate the participation equation, the small weeks worked equation,
and the total weeks of work equation.33 These estimated equations
serve two purposes: (i) to test the relevance of the selection bias issue
in the context of the present investigation, and (ii) to provide the evaluator
with the necessary tool to shed more light on the importance of small
weeks in 31 Small Weeks regions. For example, a priori, we know
that a program participant's total benefits from the Project is equal to the
increase in employment earnings from additional weeks of work in the RCP plus
the extra EI benefits he or she may receive during unemployment. The estimated
coefficients of the three-equation model, along with the actual data, would
provide us with the necessary information to carry out this calculation.
The estimated equations for the evaluation model (Equations 1 to 3), along
with a list of the definitions of variables used in the model, are presented
at the end of this Appendix. Two O.L.S. equations (Equations 4 and 5), which
are the basis for the quantitative results reported in Section 6.2 of this
report, are also included here for reference. The reader may have noticed that
Equations 2 and 3 and Equations 4 and 5 have the same dependent variables and
explanatory variables. The only difference between the two sets is how they
have been estimated.34 Equations 2 and 3 have been designed to
account for the potential influence of selection bias, but Equations
4 and 5 assume the non-existence of selection bias. The no selection
bias assumption is valid if and only if the estimated coefficients of
Equations 4 and 5 are not significantly different from the estimated
coefficients of Equations 2 and 3. This has been statistically tested to be
true. We may, therefore, conclude that selection bias is not a
relevant issue for the evaluation of the Small Weeks Pilot Project.
The following is a brief summary of the salient features of the evaluation
model and its estimated equations:
- The sample size for estimating the evaluation model is extremely large.
It consists of a sample of 422,961 claimants who were either Small Weeks
program participants or comparison group members. This sample size exceeds
the usual sample size requirements for producing reliable
micro-econometric estimates. The estimated equations are robust to minor
specification changes or minor observation range changes.35 This
has been confirmed many times during the estimation process.36
- The obvious shortcoming of our (administrative) data is that it only has
a limited number of variables for personal characteristics and the
socio-economic factors. For example, HRDC administrative data has no
information on the educational attainment of claimants, their spouses'
educational attainment and income, their children's labour market
activities, etc. In this study, we have to work with what is available and
attempt to get the most out of it.
- The participation equation is based on the specification of a logistic
model. This approach ensures that the estimated probability for a
claimant's program participation is within the range of zero to 1. In
this equation, the gender and age of the claimant is included as a control
for the effects of these personal characteristics on program
participation. The regional unemployment rate of the claimant's
residence is used to capture the influence of labour market conditions on
participation probability. A set of binary variables for provinces is
included to control for the effects of provincial culture. A set of
industrial binary variables is used to control for systematic differences
in labour market conditions across industries. All estimated coefficients
except two are statistically significant at, at least, the 5 percent level
and have the expected signs. For example, a male claimant has lower
probability to be a program participant than a female claimant. The older
the individual, the less likely he or she would become a participant. On
the other hand, a region of relatively high unemployment rate tends to
induce more claimants to accept small weeks of work in the RCP.
This suggests that the demand for small weeks is largely
determined by the buoyancy (or the lack of it) of the economy. When
regular jobs are plentiful, most workers would prefer regular-hours jobs
to small weeks work. The set of binary (0 and 1) provincial
variables shed some light on provincial influence on program
participation. British Columbia is the reference province in the
equation. Thus a positive and statistical coefficient for a province means
that a claimant from this particular province has a higher probability for
program participation than a claimant from British Columbia. The pattern
is quite clear: Program participation concentrates heavily in the
Maritimes provinces; Quebec and Ontario are next; claimants from the
Prairies and B.C. have the lowest probability for engaging in small
weeks activities.
The participation equation also demonstrates that an individual's
industrial affiliation has some influence on an individual's decision on
accepting small weeks of work. Claimants from fishing, forestry,
transportation-storage-and communication, trade, and business and other
miscellaneous services have a higher probability to engage in small weeks of
work than claimants from public administration sector, agriculture, mining,
manufacturing, and finance-insurance-and real estate. Farmers and miners are
mostly seasonal workers; one may think that they would probably like some small
weeks of work during the off-seasons. Their relatively low probability in
program participation is likely determined by the lack of small weeks work
available in these sectors. Occupations in manufacturing and
finance-insurance-and real estate are mostly regular jobs. Individuals from
these sectors are unlikely small weeks participants, as suggested by
the estimated coefficients.
- The second equation of the model refers to the small weeks of
work of the claimant.37 The equation specifies that small
weeks of work depends upon a vector of personal attributes,
socio-economic factors, Employment Insurance (EI) usage (i.e., whether or not the person is a
member of new entrants or re-entrants, a repeat user,38 and or
a recipient of Family Supplement), and finally whether or not the person
is a program participant. Variables for EI usage appear in this equation
but not in the participation equation. This is based on the rationale that
EI rules directly influence a claimant's number of small weeks worked
but not necessarily the individual's participation decision. For
example, a claimant might be willing to work one small week only,
if he or she accepted more than one small week in the RCP, the
claimant's total family income would have exceeded the maximum allowed
by the Family Supplement (FS) rule and would have lost the extra income
from the FS. As noted earlier, to circumvent the potential influence of selection
bias, we have used the Heckman estimator to carry out the estimation.39 The estimated coefficient for the participation variable is 1.97.
This means that, after controlling for the influences of all other
factors, the Project increases a typical program participant's small
weeks of work by 1.97 weeks. Similar to the participation equation,
with very few exceptions, the estimated coefficients for this equation
have the expected signs and are statistically highly significant. Their
interpretation is straightforward, and will not be elaborated here.
- The last equation models total weeks of work equation. As
contended earlier, for program participants, a small week of work
could lead to additional weeks of work with the same firm in the RCP. This
equation is designed to capture this indirect effect of the Project.
In the specification, this indirect effect is captured by the interaction
term of small weeks worked * program participation. Once again, to
purge any possible influence of selection bias, we have used the
Heckman estimator to estimate the coefficients of this equation. The
estimated coefficient for this variable is 0.22, which is extremely close
to its counterpart of 0.23 estimated by the O.L.S. used in the first
approximation section. This result, along with the evidence from the
second equation of the model, confirms that selection bias is a
non-issue for this investigation.
Evaluation model: Estimated equations
Equation #1 (model component): Probability of
participation* |
Dependent Variable (PARTICIPATION): With weeks of work
earning less than $150 per week in the RC=1, otherwise=0
Sample: 422,961 cases
Cases included in analysis: 417,017
Method: Maximum likelihood — binary logit |
Variable** |
Coefficient |
Standard Error |
Z-Statistic |
Significance |
CONSTANT |
-17.569 |
0.096 |
-182.052 |
0.000 |
MALE |
-0.435 |
0.015 |
-27.570 |
0.000 |
AGE |
-0.007 |
0.001 |
-10.583 |
0.000 |
URATE |
2.037 |
0.010 |
202.554 |
0.000 |
NFL |
2.778 |
0.140 |
19.839 |
0.000 |
PEI |
1.650 |
0.616 |
2.676 |
0.007 |
NS |
1.784 |
0.034 |
52.491 |
0.000 |
NB |
7.710 |
0.104 |
74.161 |
0.000 |
QUE |
1.658 |
0.020 |
83.314 |
0.000 |
ONT |
2.252 |
0.025 |
89.746 |
0.000 |
MAN |
-3.089 |
0.636 |
-4.860 |
0.000 |
SASK |
-3.089 |
0.241 |
-12.811 |
0.000 |
ALB |
-3.431 |
0.120 |
-28.679 |
0.000 |
TERRITORIES |
0.176 |
1.145 |
0.154 |
0.878 |
AGRI |
-0.195 |
0.057 |
-3.424 |
0.001 |
FISHING |
1.881 |
0.191 |
9.837 |
0.000 |
FORESTRY |
0.302 |
0.095 |
3.167 |
0.002 |
MINING |
-1.129 |
0.131 |
-8.633 |
0.000 |
MANUF |
-0.307 |
0.042 |
-7.255 |
0.000 |
CONS |
-0.582 |
0.047 |
-12.478 |
0.000 |
TRS_ST_COM |
0.290 |
0.048 |
5.983 |
0.000 |
TRADE |
0.272 |
0.043 |
6.397 |
0.000 |
FIN_INS_RE |
-0.423 |
0.056 |
-7.558 |
0.000 |
BUS_SER |
0.088 |
0.046 |
1.889 |
0.059 |
ED_HEALTH |
0.010 |
0.044 |
0.223 |
0.823 |
OTH_SER |
0.348 |
0.043 |
8.160 |
0.000 |
Probability (LR stat) = 0.000; McFadden R-squared = 0.765
* For the definitions of all variables, see the mnemonic list at the
end of this Appendix.
** “FEMALE”, “BC”, and “GOVERNMENT” are the binary-reference
variables for gender, province, and industrial classification in
estimation. They are not included on the mnemonic list. |
Equation #2 (model component): Small Weeks worked* |
Dependent Variable (EXC_SW): Weeks of work of earnings less
than $150 per week
Sample: 422,961 cases
Cases included in analysis: 417,017
Method: Heckman´s instrumental variable estimator |
Variable** |
Coefficient |
Standard Error |
Z-Statistic |
Significance |
CONSTANT |
-1.154 |
0.021 |
-55.722 |
0.000 |
MALE |
-0.288 |
0.006 |
-45.782 |
0.000 |
AGE |
-0.000 |
0.000 |
0.063 |
0.950 |
URATE |
0.145 |
0.002 |
96.582 |
0.000 |
NEW_REENT |
0.165 |
0.019 |
8.535 |
0.000 |
REPEAT |
0.236 |
0.006 |
37.977 |
0.000 |
FS |
-0.153 |
0.010 |
-15.688 |
0.000 |
NFL |
0.420 |
0.019 |
21.659 |
0.000 |
PEI |
0.605 |
0.027 |
22.696 |
0.000 |
NS |
0.469 |
0.015 |
31.670 |
0.000 |
NB |
0.615 |
0.017 |
36.416 |
0.000 |
QUE |
0.285 |
0.011 |
25.041 |
0.000 |
ONT |
0.247 |
0.009 |
26.267 |
0.000 |
MAN |
0.303 |
0.015 |
19.659 |
0.000 |
SASK |
0.194 |
0.0171 |
11.353 |
0.000 |
ALB |
0.214 |
0.011 |
18.893 |
0.000 |
TERRITORIES |
-1.722 |
0.098 |
-17.652 |
0.000 |
REG_CLAIM |
0.107 |
0.008 |
13.680 |
0.000 |
AGRI |
-0.124 |
0.023 |
-5.412 |
0.000 |
FISHING |
-0.985 |
0.033 |
-29.655 |
0.000 |
FORESTRY |
-0.417 |
0.034 |
-12.219 |
0.000 |
MINING |
-0.092 |
0.026 |
-3.571 |
0.000 |
MANUF |
-0.156 |
0.014 |
-10.840 |
0.000 |
CONS |
-0.058 |
0.016 |
-3.677 |
0.000 |
TRS_ST_COM |
-0.001 |
0.017 |
-0.034 |
0.973 |
TRADE |
0.304 |
0.015 |
20.552 |
0.000 |
FIN_INS_RE |
0.103 |
0.019 |
5.298 |
0.000 |
BUS_SER |
0.064 |
0.017 |
3.837 |
0.000 |
ED_HEALTH |
-0.129 |
0.015 |
-8.630 |
0.000 |
OTH_SER |
0.209 |
0.015 |
14.105 |
0.000 |
PARTICIPATION |
1.971 |
0.015 |
131.141 |
0.000 |
Probability (F-statistic) = 0.000; adjusted R-squared =
0.435; Durbin-Watson = 1.995
* For the definitions of all variables, see the mnemonic list at the
end of this Appendix.
** “FEMALE”, “BC”, and “GOVT” are the binary-reference
variables for gender, province, and industrial classification in
estimation. They are not included on the mnemonic list. |
Equation #3 (model component): Total weeks of work* |
Dependent Variable (WKS_STAT): Total weeks of work in the
RCP Sample: 422,961 cases
Cases included in analysis: 422,961
Method: Heckman´s instrumental variable estimator |
Variable** |
Coefficient |
Standard Error |
Z-Statistic |
Significance |
CONSTANT |
26.764 |
0.025 |
1051.994 |
0.000 |
MALE |
-0.431 |
0.008 |
-53.433 |
0.000 |
AGE |
-0.001 |
0.000 |
2.112 |
0.034 |
URATE |
-0.216 |
0.003 |
-77.440 |
0.000 |
NFL |
-0.557 |
0.028 |
-20.147 |
0.000 |
PEI |
-1.165 |
0.039 |
-29.891 |
0.000 |
NS |
-0.056 |
0.022 |
-2.606 |
0.009 |
NB |
-1.177 |
0.025 |
-46.679 |
0.000 |
QUE |
-0.136 |
0.016 |
-8.515 |
0.000 |
ONT |
-0.061 |
0.013 |
-4.541 |
0.000 |
MAN |
-0.122 |
0.022 |
-5.533 |
0.000 |
SASK |
-0.171 |
0.024 |
-6.985 |
0.000 |
ALB |
-0.281 |
0.016 |
-17.699 |
0.000 |
TERRITORIES |
1.567 |
0.141 |
11.110 |
0.000 |
EXC_SW* |
|
PARTICIPATION |
0.219 |
0.008 |
28.550 |
0.000 |
Probability (F-statistic) = 0.000; adjusted R-squared =
0.085; Durbin-Watson = 1.999
* For the definitions of all variables, see the mnemonic list at the
end of this Appendix.
** “FEMALE”, “BC”, and “GOVT” are the binary-reference
variables for gender, province, and industrial classification in
estimation. They are not included on the mnemonic list. |
Equation #4 (supplementary equation): Small Weeks
worked* |
Dependent Variable (EXC_SW): Weeks of work of earnings less
than $150 per week in the RCP Sample: 422,961 cases
Cases included in analysis: 417,017
Method: Ordinary least squares |
Variable** |
Coefficient |
Standard Error |
Z-Statistic |
Significance |
CONSTANT |
-1.152 |
0.020 |
-57.865 |
0.000 |
MALE |
-0.283 |
0.006 |
-46.492 |
0.000 |
AGE |
-0.000 |
0.000 |
1.784 |
0.075 |
URATE |
0.146 |
0.001 |
115.746 |
0.000 |
NEW_REENT |
0.143 |
0.019 |
7.601 |
0.000 |
REPEAT |
0.192 |
0.006 |
31.870 |
0.000 |
FS |
-0.154 |
0.009 |
-16.272 |
0.000 |
NFL |
0.425 |
0.019 |
22.567 |
0.000 |
PEI |
0.615 |
0.026 |
24.044 |
0.000 |
NS |
0.475 |
0.014 |
33.426 |
0.000 |
NB |
0.625 |
0.016 |
39.677 |
0.000 |
QUE |
0.292 |
0.010 |
28.169 |
0.000 |
ONT |
0.246 |
0.009 |
27.024 |
0.000 |
MAN |
0.305 |
0.015 |
20.464 |
0.000 |
SASK |
0.195 |
0.017 |
11.818 |
0.000 |
ALB |
0.214 |
0.011 |
19.623 |
0.000 |
TERRITORIES |
-1.736 |
0.095 |
-18.356 |
0.000 |
REG_CLAIM |
0.095 |
0.008 |
12.439 |
0.000 |
AGRI |
-0.116 |
0.022 |
-5.246 |
0.000 |
FISHING |
-0.980 |
0.032 |
-30.417 |
0.000 |
FORESTRY |
-0.409 |
0.033 |
-12.330 |
0.000 |
MINING |
-0.087 |
0.025 |
-3.465 |
0.000 |
MANUF |
-0.155 |
0.014 |
-11.140 |
0.000 |
CONS |
-0.047 |
0.015 |
-3.083 |
0.002 |
TRS_ST_COM |
0.002 |
0.017 |
0.129 |
0.898 |
TRADE |
0.299 |
0.014 |
20.842 |
0.000 |
FIN_INS_RE |
0.097 |
0.019 |
5.111 |
0.000 |
BUS_SER |
0.063 |
0.016 |
3.903 |
0.000 |
ED_HEALTH |
-0.127 |
0.015 |
-8.710 |
0.000 |
OTH_SER |
0.208 |
0.014 |
14.463 |
0.000 |
PARTICIPATION |
1.975 |
0.009 |
210.652 |
0.000 |
Probability (F-statistic) = 0.000; adjusted R-squared =
0.468; Durbin-Watson = 1.999
* For the definitions of all variables, see the mnemonic list at the
end of this Appendix.
** “FEMALE”, “BC”, and “GOVT” are the binary-reference
variables for gender, province, and industrial classification in
estimation. They are not included on the mnemonic list. |
Equation #5 (supplementary equation) : Total weeks
of work* |
Dependent Variable (WKS_STAT): Total weeks of work in the
RCP Sample: 422,961 cases
Cases included in analysis: 422,961
Method: Ordinary least squares |
Variable** |
Coefficient |
Standard Error |
Z-Statistic |
Significance |
CONSTANT |
26.737 |
0.022 |
1242.911 |
0.000 |
MALE |
-0.395 |
0.008 |
-50.346 |
0.000 |
AGE |
-0.001 |
0.000 |
2.509 |
0.012 |
URATE |
-0.218 |
0.002 |
-126.932 |
0.000 |
NFL |
-0.557 |
0.027 |
-20.471 |
0.000 |
PEI |
-1.171 |
0.037 |
-31.459 |
0.000 |
NS |
-0.095 |
0.021 |
-4.593 |
0.009 |
NB |
-1.184 |
0.022 |
-52.889 |
0.000 |
QUE |
-0.172 |
0.014 |
-11.921 |
0.000 |
ONT |
-0.055 |
0.013 |
-4.118 |
0.000 |
MAN |
-0.095 |
0.022 |
-4.366 |
0.000 |
SASK |
-0.143 |
0.024 |
-5.920 |
0.000 |
ALB |
-0.254 |
0.016 |
-16.278 |
0.000 |
TERRITORIES |
1.646 |
0.138 |
11.903 |
0.000 |
EXC_SW* |
|
PARTICIPATION |
0.234 |
0.002 |
109.417 |
0.000 |
Probability (F-statistic) = 0.000; adjusted R-squared =
0.108; Durbin-Watson = 1.998
* For the definitions of all variables, see the mnemonic list at the end
of this Appendix.
** “FEMALE”, “BC”, and “GOVT” are the binary-reference variables
for gender, province, and industrial classification in estimation. They
are not included on the mnemonic list. |
Mnemonic list: Definitions of variables
AGE: Age of the claimant at benefit period commencement.
AGRI: Binary variable equal to 1, if the claimant's industrial
affiliation is agriculture, otherwise equal to 0.
ALB: Binary variable equal to 1, if the claimant's most recent
residence is Alberta, otherwise equal to 0.
BUS_SER: Binary variable; equal to 1, if the claimant's industrial
affiliation is business services, otherwise equal to 0.
CONS: Binary variable; equal to 1, if the claimant's industrial
affiliation is construction, otherwise equal to 0.
ED_HEALTH: Binary variable; equal to 1, if the claimant's
industrial affiliation is education, health, and related services,
otherwise equal to 0.
EXC_SW: Number of small weeks (weekly earnings less than $150 per
week) of work in the RCP.
FIN_INS_RE: Binary variable; equal to 1, if the claimant's
industrial affiliation is finance, insurance and real estate, otherwise
equal to 0.
FISHING: Binary variable; equal to 1, if the claimant's industrial
affiliation is fishing and trappings, otherwise equal to 0.
FORESTRY: Binary variable; equal to 1, if the claimant's industrial
affiliation is forestry, otherwise equal to 0.
FS: Binary variable; equal to 1, if the claimant is a recipient of EI
Family Supplement, otherwise equal to 0.
MALE: Binary variable; equal to 1, if the claimant's gender is
male, otherwise equal to 0.
MAN: Binary variable equal to 1, if the claimant's most recent
residence is Manitoba, otherwise equal to 0.
MANUF: Binary variable; equal to 1, if the claimant's industrial
affiliation is manufacturing, otherwise equal to 0.
MINING: Binary variable; equal to 1, if the claimant's industrial
affiliation is mines, quarries, and oil wells, otherwise equal to
0.
NB: Binary variable equal to 1, if the claimant's most recent
residence is New Brunswick, otherwise equal to 0.
NEW_REENT: Binary variable; equal to 1, if the claimant is a member
of EI's new entrant and re-entrant group, otherwise equal to 0.
NFL: Binary variable equal to 1, if the claimant's most recent
residence is Newfoundland, otherwise equal to 0.
NS: Binary variable equal to 1, if the claimant's most recent
residence is Nova Scotia, otherwise equal to 0.
ONT: Binary variable equal to 1, if the claimant's most recent
residence is Ontario, otherwise equal to 0.
OTH_SER: Binary variable; equal to 1, if the claimant's industrial
affiliation is services other than public administration and defense
and the service industries listed, otherwise equal to 0.
PARTICIPATION: Binary variable; equal to 1, if the claimant has some small
weeks (weekly earnings less than $150 per week) of work in the RCP,
otherwise equal to 0.
PEI: Binary variable equal to 1, if the claimant's most recent
residence is Prince Edward Island, otherwise equal to 0.
QUE: Binary variable equal to 1, if the claimant's most recent
residence is Quebec, otherwise equal to 0.
REG_CLAIM: Binary variable; equal to 1, if the person is a regular
EI benefits claimant, otherwise equal to 0.
REPEAT: Binary variable; equal to 1, if the claimant at the time of
filing a new EI claim has had 5 weeks or more weeks of regular EI
benefits since July 1, 1996, otherwise equal to 0.
SASK: Binary variable equal to 1, if the claimant's most recent
residence is Saskatchewan, otherwise equal to 0.
TERRITORIES: Binary variable equal to 1, if the claimant's most
recent residence is Northwest Territories or Yukon, otherwise equal to
0.
TRADE: Binary variable; equal to 1, if the claimant's industrial
affiliation is wholesale or retail trade, otherwise equal to 0.
TRS_ST_COM: Binary variable; equal to 1, if the claimant's
industrial affiliation is transportation, storage, communication, and other
utilities, otherwise equal to 0.
URATE: Regional unemployment rate of where the claimant resides.
Footnotes
30 |
There are two versions of the Heckman estimator. The first one uses the
participation equation to calculate the Inverse Mills Ratio, and then
include the Ratio as one of the explanatory variables in the outcome
equations. The second version is essentially an instrumental variable
method. It uses the participation equation to calculate the probability of
program participation, and then use this calculated series as an
instrumental variable to replace the participation variable (explanatory
variable) in the outcome equations. The instrumental variable approach is
used in our estimation.
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31 |
For a more detailed discussion of the Heckman evaluation model, see
Heckman (1979).
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32 |
The sample consists of 162,830 participating claims from 31 Small Weeks
regions and 260,131 claims (comparison group) randomly selected from the
rest of the country.
|
33 |
The term small weeks of work refers to the small
weeks in the RCP that would be excluded for benefit calculation
purposes for program participants. Total weeks of work denotes the
sum of small weeks and regular weeks of work in the RCP.
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34 |
In particular, Equations 2 and 3 have been estimated with the Heckman
estimator (instrumental variable), whereas Equations 4 and 5 have been
estimated with the O.L.S. method.
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35 |
For example, if we randomly drop 10 percent of the claimants from the
sample and re-estimate the model, the estimated equation would have
remained more or less the same as the equations from the full sample.
|
36 |
The sample size and the actual number of cases included in estimating
each equation vary slightly. This is because a few cases miss information
for all explanatory variables. The computer program therefore
automatically excludes these few cases from the sample during estimation.
Since the three estimated equations of the model do not use the same list
of explanatory variables, the actual number of cases included in
estimating the equations vary slightly.
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37 |
A small week is defined as a week with earnings less than $150.
For a more detailed explanation of this dependent variable, see the
footnotes of Table 3.
|
38 |
See footnote #27.
|
39 |
See footnote #30.
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