Data
This study uses nationally representative data from the Survey of Income and Program Participation (SIPP) 1996, 2001, and 2004 panels. Each panel lasted 3 to 4 years, and respondents were interviewed every 4 months to collect employment, income, and program participation information from the previous 4 months. The three nonoverlapping panels are stacked together to observe the trajectories of families from 1995 to 2007, a period covering 1–2 years prior to and 10 years after TANF implementation.Footnote 7 Although it would have been ideal to trace even longer-term trajectories after 2007, the Great Recession and subsequent changes in TANF policy rules complicate the identification of long-term trajectories in the post-2008 period.Footnote 8 This study examines the impacts of TANF policies on women who had not received any college education (a high school degree or less) at the time of policy implementation (described in the sample section below), and information from subsequent panels serves as the follow-up for women observed in the 1996 panel. I summarize the SIPP data into annual information to address the seam bias in the SIPP data (Moore 2008). Annual information also helps depict trends over time, avoiding the volatile fluctuations in earnings, labor supply, and program participation status that would have arisen had the data been structured monthly or quarterly. The SIPP is an ideal dataset for this study for three reasons. First, it provides rich information on labor force performance, welfare usage, and sociodemographic characteristics. Second, topical modules on fertility history, marital history, education and training history, and migration history provide crucial information for this study in regard to identifying individuals most likely to be affected by the welfare reform. This information is not available in other major national household surveys collecting employment and income information, such as the Current Population Survey (CPS) or the American Community Survey. Third, the SIPP is known to have lower underreporting rates of welfare participation rates when compared to the CPS and Panel Study of Income Dynamics (Meyer et al. 2009). Fourth, the SIPP tracks individuals who moved out of households at their new addresses, which is beneficial for studying long-term trajectories.
Sample
Individuals most likely to be affected by TANF policies are unmarried mothers with low levels of education (Kaushal and Kaestner 2001). It has been shown that 94% of TANF recipients had 12 or fewer years of education and 87% were not married (ACF 2012). The affected group or treatment group in this study is hence defined as unmarried mothers with a high school degree or lower levels of education. The comparison group is married mothers with a high school degree or lower levels of education. Specifically, I retain samples who are female, were not born abroad,Footnote 9 have lived in their current state of residence since before 1996, and did not move during the panel (reasons detailed in the "Empirical strategies" section). I exclude individual observations from years in which samples were enrolled in school for more than one-third of the observed months in a year.Footnote 10 Additionally, utilizing the individual history information collected in the SIPP topical module enables this study to restrict the samples to women who were aged 18–45 years, had a child below 18 years of age, and had a high school degree or a lower level of education at the time of TANF implementation in a given state. The marital status used to define the treatment and comparison groups is also based on marital history information that indicates marital status at the time of TANF implementation in a given state. For instance, at the end of the 2004 panel (year 2007), the age range of mothers was 30–57, and some of the unmarried mothers may have become married, acquired a college degree, or had children aged older than 18 years.Footnote 11 The inclusion criteria are only imposed on mothers’ characteristics at the time of policy implementation. In total, 3995 unmarried mothers (or 14,528 observations) and 6214 married mothers (or 23,618 observations) met the inclusion criteria. Another comparison group used in prior studies on welfare reform was unmarried women without children. This is not an ideal comparison group in this study focusing on long-term trajectories because some unmarried women without children at the time of TANF implementation gave birth in the subsequent period, and child birth is a stronger driver of a decrease in labor supply when compared to a change in marital status (Cohen and Blanchi 1999).
Measures
The main outcomes of this study capture three dimensions: welfare participation (participation in TANF and other welfare programs, such as the Supplemental Nutrition Assistance Program [SNAP] and Supplemental Security Income [SSI]), labor supply (employment status and average monthly hours worked), and income (average monthly earnings and total family income). Furthermore, this study examines one additional outcome: financial independence. Financial independence is defined as not receiving financial support from relatives, friends, or welfare programs, such as TANF, SNAP, and SSI. This outcome investigates whether or not families are financially independent from public and private support.
The dependent variables are coded using the following definitions. First, TANF participation is defined as receiving TANF in any month of the year. Second, SNAP and SSI participation is defined as receiving any of these benefits in any month of the year. Third, employment status is coded as 1 when a person worked for some hours at any time in a year and 0 when a person did not work in a year. Fourth, monthly hours worked is constructed by multiplying the usual hours worked in a week and weeks worked in that month and averaging the monthly hours worked in that year. Fifth, log monthly total earnings are calculated through averaging monthly earnings information in a given year and then taking the log of the average monthly earnings. Sixth, log average monthly family income is calculated by averaging monthly family income (including earned income, transfer income, property income) information in a given year and then taking the log of the average monthly family income. Earnings and family income data are expressed in January 1996 currency using the Consumer Price Index. Seventh, financial independence is coded as 1 if the respondent did not receive any money from relatives, friends, TANF, SNAP, or SSI and 0 otherwise.
The main independent variables are the time indicator for long-term effects (years since state TANF implementation) and the TANF policy stringency measure. The first key independent variable is years since policy implementation or years since policy influence (YPI). This variable is the number of years relative to the timing of TANF implementation in a given state.Footnote 12 According to the study hypothesis, as time elapses since the policy implementation, if stringent TANF requirements are effective in promoting financial self-reliance, the overall trend in labor force participation and earnings will be more positive or less negative, and welfare participation will be more negative in stringent states than in other states, holding all other factors constant.
The second key independent variables, as described in the TANF policy introduction section, are measures of the stringencies of two state TANF policies: time limits and sanctions on noncompliance with work requirements. For the time limit policy, when a state has a time limit of less than 60 months for the majority of the years during the study period, this state is coded as 1; otherwise, it is coded as 0. For the sanction policy, when a state imposes sanctions on the full family at the initial incidence of noncompliance with work requirements for the majority of years during the study period, this state is coded as 1, and otherwise 0.Footnote 13 Table 1 details the policy stringency classification of each state, and Fig. 1 shows the policy features across years.Footnote 14 The data source for this variable is the Urban Institute Welfare Rules Database. I coded their textual data into numeric form.
Table 1 State TANF policy stringency measures This study additionally controls for individual characteristics and the state economic environment. Individual-level controls include time-invariant characteristics, such as single mothers’ race (White [ref.], Black, Hispanic, and other race), the age of the youngest child in the panel (0–2 [ref.], > 2 to < 6, 6 to < 12, or 12 to 18 years),Footnote 15 and time-varying characteristics, such as age (18–24 [ref.], 25–29, 30–34, 35–39, 40–45, 45–49, or 50–57 years), marital status (married or not married [ref.]), number of children (0, 1, 2 [ref.], or 3 or more), and household size (1, 2, 3 or 4 [ref.], or 5 or more).Footnote 16 The state environment is measured by a range of state characteristics in a given year, including state unemployment rates, state EITC maximum benefits as percent of federal EITC (Tax Credits for Workers and Their Families 2015), and a range of TANF state policy characteristics (e.g., maximum income eligibility for a family of three, maximum benefits for a family of three with no income, whether or not a family cap policy exists, age of a child [in months] until which the mother could be exempted from work requirements), and state fixed effects.
Empirical Strategies
There are five major factors that may confound the relationships between welfare stringency in time limits and sanctions and the observed differences in welfare use, labor supply, and income: preexisting differences between states that adopted stringent policies and those that did not, differences due to changes in economic conditions and policies over time, cross-state migration in response to policies, waiver policies, and states that changed TANF policy rules during the study period. First, states’ decisions on TANF policy rules are often driven by various state characteristics, including economic circumstances, political ideology, or racial composition (De Jong et al 2006), and individual welfare use, labor supply, and income trajectories are embedded in state environments. To adjust for preexisting differences between states that adopted stringent policies and those that did not, I use state fixed effects models to address this source of bias. State fixed effects control for state differences that are constant over time.
Second, time-variant changes across states are another factor that may confound the trajectories observed in this study. To address this problem, I control for state unemployment rates in each responding state and year to account for influences of state economic environments. In addition, as mentioned above, several time-variant state policy characteristics are controlled for: state EITC maximum benefits as percent of federal EITC (Tax Credits for Workers and Their Families 2015) and a range of TANF state policy characteristics.Footnote 17 In sensitivity analyses, I additionally control for state SNAP policy characteristics (described in detail in the sensitivity analysis section). This modeling approach helps ensure that the associations between time limits and sanction policies are not confounded by other observable economic and policy characteristics. Furthermore, I control for individual time-variant characteristics, such as marital status and household composition, to account for differential trends in marital and fertility patterns across stringent and non-stringent states.Footnote 18 Despite these attempts, there could still be other unobserved time-variant factors correlated with state policy stringencies that affect the association between stringency levels and long-term welfare use, labor supply, and income trajectories. I adopt the DDD design to account for unobserved time-variant state characteristics (e.g., childcare resources) that similarly affect both unmarried and married low-educated mothers. In addition, I include a model that controls for state-specific linear trend, which accounts for the state trend of an outcome among low-educated mothers.Footnote 19
Third, in terms of cross-state migration, state TANF policies may encourage interstate migration, and this may bias the trajectories observed in this study. Studies have documented that lenient welfare policies may attract disadvantaged families to move into the state (McKinnish 2005), and stringent policies may push low-income families to migrate out of the state (De Jong et al. 2005). Restricting the sample to those who had lived in a state prior to the welfare reform allows this study to exclude respondents who migrated into states that did not adopt stringent policies after the reform and to more accurately capture long-term relationships.Footnote 20 However, this residence restriction cannot account for effects from disadvantaged mothers who moved out of a state with stringent policies, so observed trajectories of stringent policies might underestimate welfare use and overestimate labor supply and earned income. Nevertheless, the magnitude of migration as a result of welfare policies is found to be small (Bailey 2005; Goodman 2017; Kaushal 2005; Schram et al. 1998). Additionally, excluding respondents who moved to another state after the reform is necessary when measuring the long-term patterns for another reason. For a person who moves from one type of state to another, his or her welfare use, labor supply, and income trajectories over time would not reflect behavioral responses to a particular type of policy. For example, if a person moves out of a state with a shorter time limit or a stricter sanction during the fifth year after TANF policy implementation, his or her outcome during the sixth year will not reflect his or her response to a particular policy in the sixth year. The residence restriction employed in this study allows the proper tracking of individual trajectories over time.Footnote 21
Fourth, as mentioned earlier, many states implemented waiver policies prior to the welfare reform, which may affect the trajectories examined in this study. For instance, five states adopted time limits shorter than 60 months, and two states adopted full-family sanction policies between 1993 and 1995 (Grogger and Karoly 2005). Although requirements in these states may have changed after the reform, the work and welfare use trajectories of single mothers since the reform likely differ from those of their counterparts living in states without waiver policies, as those living in states with waiver policies were exposed to components of the reform earlier. I address this potential bias through two ways. First, I control for state fixed effects in all models, which adjust for fixed characteristics related to the adoption of waiver policies. Second, in one model, I exclude states that adopted any waiver policy prior to 1996 from the analyses.
Fifth, as shown in Fig. 1, a number of states changed TANF policy rules during the study period. In terms of time limits, Montana transitioned from having a time limit below 60 months to having a time limit of 60 months, and Delaware transitioned into having a time limit below 60 months. With respect to sanctions, seven states that did not have full sanctions in the majority of years during the study period adopted full sanctions in other years, and two states transitioned into having full sanctions. I classified these states based on their policy environments in most years during the study period, but these transitions may affect the trajectories examined in this study. Therefore, in sensitivity analyses, I conduct additional analyses excluding states that experienced transitions in time limit and sanction policies during the study period, and the results are presented in Appendix 2 Tables.
In this study, the samples of focus are low-skilled single mothers, regardless of their status in regard to TANF benefits recipiency. Mothers not receiving TANF are included in this study for two reasons. First, the effect of the TANF policy requirements may or may not go through the actual participation in TANF. Taking TANF nonparticipants as an example, as described in the mechanisms section, they may prefer to work more and not use welfare to save their time limit quota or to avoid the hassle of dealing with TANF behavioral requirements. Behavioral responses to policy characteristics may not go through the actual program participation. Second, TANF policy stringencies are correlated with program participation rates. Participants in states with more stringent requirements are, on average, more disadvantaged than participants in states without stringent requirements; for example, they tend to have worse health and higher rates of disability (Moffitt et al. 2001; Frogner et al. 2009). If the samples that receive TANF benefits were the focus, the comparison between states with or without stringent policies would be a case of comparing apples and oranges. Both reasons point to the importance of including both TANF-participating and nonparticipating mothers, so this study could capture the full range of relationships between TANF policy stringencies and outcomes.
I adopt the DDD design to account for unobservable time-variant factors that correlate with outcomes or TANF policy characteristics. Following various studies, low-educated unmarried mothers at the time of TANF policy implementation are selected to be the treatment group, and their married motherFootnote 22 counterparts are chosen as the comparison group (Bitler et al. 2005; Kaushal and Kaestner 2001). Married mothers were less affected because married mothers likely had household incomes that were too high to qualify for TANF, so their outcomes may serve as approximate reference points in understanding the extent of the policy effects on single mothers. One complication of the longitudinal analysis is that mothers’ marital status may change over time. Mothers who were married at the time of the welfare reform may later separate or divorce from their spouses, and single mothers may become married later and have a lower likelihood of qualifying for TANF. I control for time-varying marital status, number of children, and household size to account for the differential trends in marriage across states over time.Footnote 23 The first difference is the difference in outcomes (Y) before and after the welfare reform (\(Y_{2} - Y_{1}\)), the second difference is between unmarried (U) and married (M) mothers ([\(Y_{U2} - Y_{U1} - Y_{M2} - Y_{M1}\)]), and the third difference is between states with stringent policies (S) and states without stringent policies (more lenient; L){([\(Y_{SU2} - Y_{SU1}\))] − [\(Y_{SM2} - Y_{SM1}\)]) − ([\(Y_{LU2} - Y_{LU1}\))]- [\(Y_{LM2} - Y_{LM1}\)])}. The validity of the difference-in-difference research design requires that the trends in outcomes between the treatment and comparison groups would have been similar in the absence of policy. I test this parallel trend assumption by comparing trends in outcomes between married and unmarried mothers prior to the implementation of TANF. The results presented in Appendix Table 10 indicate that married mothers are a suitable comparison group, as suggested by prior studies (Bitler et al. 2005; Kaushal and Kaestner 2001).Footnote 24 One may argue that single and married mothers may differ in their patterns of outcomes as they and their children grow older. To address this concern, I also present the first difference results in Appendix 2 Tables, allowing the examination of whether the results are driven by changes in the treatment or comparison group mothers.
I use two types of models in the empirical analysis. First, for the earned income and work hours outcomes, I use the Heckman selection model (detailed in the last part of the empirical strategies section). Second, for all other outcomes, I use a three-level multilevel model to examine the differential long-term welfare use, labor supply, and income progress between low-skilled unmarried and married mothers in states with stringent time limits and sanctions and states without. Multilevel models have the strength of adjusting for the clustering nature of data and allowing the standard errors to be more robust (Raudenbush and Bryk 2002). In this study, observations at each time point/in each year (level 1) are nested within individuals (level 2), and individuals are nested within states (level 3). Below, I describe the model for each level. The level 1 model is as follows:
$${Y_{tis}} = {\beta _{0is}} + \sum {{\beta _{1is}}} YP{I_{tis}} + \sum {{\beta _{2is}}} {X_{{tis}}} + \sum {{\beta _{3is}}} {S_{tis}} + {\varepsilon _{tis}}\quad{\varepsilon _{tis}}\sim N(0,\sigma _\varepsilon ^2)$$
where \({Y}_{tis}\) is the outcome for individual i in state s at time t. Each outcome is regressed on time categories (\({YPI}_{tis}\)), so a vector of \({\beta }_{1is}\) captures how the outcomes change with years elapsed since TANF implementation.Footnote 25\({X}_{tis}\) represents a vector of time-variant individual or household characteristics,Footnote 26 and \({S}_{tis}\) represents a vector of state time-variant characteristics in state s at time t.Footnote 27\({\beta }_{0is}\) is the mean of an outcome across time points for person i in state s, and the error term is noted as \({\varepsilon }_{tis}\), which is assumed to be independent and to conform to normal distribution, with a mean of 0 and variance of \({\sigma }_{\varepsilon }^{2}\). The level 2 model is as follows:
$${\beta _{{0_{is}}}} = {\gamma _{{0_{0s}}}} + {\gamma _{{0_{1s}}}}Trea{t_{is}} + \sum {{\gamma _{{0_{2s}}}}} {X_{is}} + {\zeta _{{0_{is}}}}\;\;{\zeta _{{0_{is}}}}\sim N(0,\sigma _{{\zeta _0}}^2)$$
$$ \beta_{1is} = \gamma_{10s} + \gamma_{11s} Treat_{is} $$
$$ \beta_{2is} = \gamma_{20s} $$
$$ \beta_{3is} = \gamma_{30s} + \gamma_{31s} Treat_{is} $$
where \({Treat}_{is}\) is the treatment status, with women who were single mothers at time of TANF policy implementation in state s coded as 1 and those who were married mothers coded as 0. A vector of \({X}_{is}\) represents individual time-invariant characteristics.Footnote 28\({\gamma }_{00s}\) is the mean of the outcome across individuals in state s, and \({\zeta }_{0is}\) represents the random intercept specific to the individual i. \({\gamma }_{11s}\) are the interactions between treatment status (\({Treat}_{is}\)) and years since policy influence categories (\(\sum{YPI}_{tis}\)), and this vector of coefficients estimates the differences in outcomes between unmarried and married mothers across YPIs regardless of time limits and sanction policy characteristics. \({\gamma }_{31s}\) are the interactions between treatment status (\({Treat}_{is}\)) and a vector of state time-variant characteristics (\(\sum{S}_{tis}\)). These interactions allow coefficients for state characteristics to vary for treatment and comparison groups to account for the confounding effects of other state characteristics. The level 3 model is as follows:
$${\gamma }_{00s}={b}_{000}+\sum{b}_{001}{State}_{s}+ {\eta }_{00s}\quad {\eta }_{00s}\sim N\left(0,{\sigma }_{{\eta }_{0}}^{2}\right)$$
$${\gamma }_{01s}={b}_{010}+{{b}_{012}FullSC}_{s}+{{b}_{013}TL<60}_{s}$$
$${\gamma }_{02s}={b}_{020}$$
$${\gamma }_{10s}={b}_{100}+{{b}_{101}FullSC}_{s}+{{b}_{102}TL<60}_{s}$$
$${\gamma }_{11s}={b}_{110}+ {{b}_{111}FullSC}_{s}+{{b}_{112}TL<60}_{s}$$
$${\gamma }_{20s}={b}_{200}$$
$${\gamma }_{30s}={b}_{300}$$
$${\gamma }_{31s}={b}_{310}$$
where \({b}_{000}\) is the average outcome level across states, a vector of \({b}_{001}\) captures state fixed effects,Footnote 29 and \({\eta }_{00s}\) represents state-specific random intercepts. The coefficients \({b}_{012}\) and \({b}_{013}\) represent the interactions between treatment status and the TANF policy characteristics of interest, a time limit that is shorter than 60 months (\({TL<60}_{s}\)) and a full sanction on noncompliance with work requirements (\({FullSC}_{s}\)). The omitted category here is states without strict time limits or full sanction policies. \({b}_{101}\) and \({b}_{102}\) represent the interactions between time limit/sanction policy characteristics with the vector of years since policy influence categories (\(\sum{YPI}_{tis}\)). The main coefficients of interests in this study are \({b}_{111}\) and \({b}_{112}\): the three-way interactions between state TANF policy stringencies (\({FullSC}_{s}\) and \({TL<60}_{s}\)), treatment status (\({Treat}_{is}\)), and years since policy influence (\({YPI}_{tis}\)). These coefficients (\({b}_{111}\) and \({b}_{112}\)) show whether the differences between low-skilled unmarried mothers and married mothers in welfare use, labor supply, and income trajectories vary over time by the TANF policy environment in which they live.
The level 1, 2, and 3 equations can be combined into a single equation or a composite model/reduced form, as follows:
$${Y_{tis}} = {b_{000}} + \sum {{b_{100}}} YP{I_{tis}} + {b_{010}}Trea{t_{is}} + \sum {{b_{00.}}} Stat{e_s} + \sum {{b_{110}}} YP{I_{tis}}xTrea{t_{is}} + \sum {{b_{101}}} YP{I_{tis}}xFullS{C_s} + \sum {{b_{102}}} YP{I_{tis}}xTL < {60_s} + \sum {{b_{011}}} Trea{t_{is}}xFullS{C_s} + \sum {{b_{012}}} Trea{t_{is}}xTL < {60_s} + \sum {{b_{111}}} Trea{t_{is}}xYR{S_{tis}}xFullS{C_s} + \sum {{b_{112}}} Trea{t_{is}}xYR{S_{tis}}xTL < {60_s} + \sum {{b_{200}}} {X_{tis}} + \sum {{b_{300}}} {S_{ts}} + \sum {{b_{310}}} Trea{t_{is}}x{S_{ts}} + \sum {{b_{020}}} {X_{is}} + {\zeta _{0is}} + {\eta _{00s}} + {\varepsilon _{tis}}$$
where vectors of \({b}_{111}\) and \({b}_{112}\) are the main coefficients of interest, which represent the cross-level interactions between TANF policy stringencies (state-level), treatment status (individual-level) and YPI categories. The vector of \({b}_{110}\) estimates the differences in unmarried and married low-educated mothers’ trajectories of outcomes shared across all states.Footnote 30
Second, for the earned income and hours worked outcomes, I use the Heckman two-step model to adjust for selection bias into employment (Heckman 1979). For instance, if more stringent policies lead to a higher employment rate, analyses of earnings or work hours would be affected by the employment rates. In the first stage, I use the same set of covariates in the DDD model as instrumental variables to predict the probability of being employed; in the second stage, in addition to including the same set of covariates, the model corrects for selection by including an explanatory variable, an inverse Mill’s ratio, that predicts individuals’ probability of selection into employment.