Robustness checks

Dans le document Essays on location choice: agglomeration, amenities and housing (Page 38-49)

productivity and urban amenities?

1.5 Empirical results

1.5.3 Robustness checks

Alternative measure: local access to cultural goods and services

In the baseline analysis, I measure culture as the share of workers whose main working task is to create or disseminate goods and services with a cultural and artistic content. This measure is basically an approximation of the labor input used to supply cultural goods and services at the local scale. However, it may not perfectly reflect the accessibility of cultural goods and services to inhabitants and firms. In defining this input measure of culture, I have eliminated workers devoted to the production of goods and services that may be easily traded – for instance in the movie or music industry – in order to focus on the production of goods that may be directly consumed locally. In this section, I

16“In any case, direct grants do not finance the bulk of artistic activity in the U.S.: they fill gaps, enhance arts education, nourish arts creation, assist in the presentation and delivery of artworks, and enable preservation. These grants thus complement, and do not replace, other means of arts funding”

(National Endowment for the Arts,2012)

propose an alternative variable that directly measures the accessibility of cultural goods and services for local inhabitants and its variation over time. Local residents and firms can access cultural goods and services either through commercial establishments that sell these goods (such as stores) or through non-profit art organizations. I compute the total number of museums, theaters, libraries and archives as well as bookstores, prerecorded tape, CD and record stores, and motion picture and video exhibitions establishments per 1’000 inhabitants. I use indicators from the U.S. County Patterns that report the number of establishments by industry for all U.S. counties. All these establishments allow local residents to access cultural goods and services. These numbers are used as an alternative measure for cultural supply reflecting the accessibility to cultural goods and services for local residents.

The results using access to cultural goods and services as the main explanatory variable are provided in Tables 1.5 and 1.6. For the sake of simplicity, I do not report estimates on control variables since they have the same magnitude and signs across estimations and are similar to the ones described in the baseline estimations. Table 1.5 reports the estimates without city fixed effects. The coefficient associated with the three commercial establishments (book, music and video stores) are negative in both equations and most of them are statistically significant. According to the Roback model, this suggests that a higher variety or easier access to these commercial establishments might be considered as a negative production amenity. This result may be explained by a negative impact of competition (measured by the number of commercial plants per capita) on firms in these areas. Besides, stores and shops are highly land intensive such that they reduce the ability for outside firms to relocate in the city.

Interestingly, traditionalnon-profit art establishments such as libraries, archives, the-aters and museums positively affect wages and rents. However, the coefficient on museums is the only one to be statistically significant. On average, if the number of museums per resident doubles, the median wage increases by 6% and the median rent by 4%. This result is consistent with the baseline findings that culture may actually be considered as a production amenity. Estimations using a synthetic measure of access to all of these localcommercial and non-commercial establishments that supply cultural goods and ser-vices are provided in the last column. Overall, the estimated coefficients is negative and highly significant in both equations but this coefficient is driven by the negative impact of commercial stores.

Estimations including city fixed effects are reported in Table 1.6. The estimates are quite similar when using the synthetic measure of access to cultural goods and services as the associated coefficients are both negative and highly significant in the last column.

When disaggregating this explanatory variable, I find that the number of commercial es-tablishments (access to book and music stores mostly) is negatively correlated with factor prices. In contrast, the coefficients associated with non-commercial art organizations are not statistically different from zero. Therefore, the positive influence of non-profit orga-nization – e.g. museums in Table 1.5 – was mainly driven by the impact of other city characteristics that were not controlled for in the cross-section analysis.

Table1.5:Alternativemeasure:accesstoculturalgoodsandservices Accesstoculture CommercialNon-commercialAll BookstoresMusicstoresVideostoresLibrariesTheatersMuseumsestablishments Dependentvariable:Rents Culture-0.025***-0.002-0.009*0.0010.0020.006***-0.024** (0.006)(0.003)(0.005)(0.001)(0.002)(0.002)(0.010) ControlsYesYesYesYesYesYesYes CityFixedEffectsNoNoNoNoNoNoNo Observations2072207220722072207220722072 R-squared0.7520.7500.7500.7500.7500.7510.751 Dependentvariable:Wages Culture-0.035***-0.012****-0.008**0.002*0.0010.004**-0.049*** (0.004)(0.002)(0.004)(0.001)(0.001)(0.002)(0.007) ControlsYesYesYesYesYesYesYes CityFixedEffectsNoNoNoNoNoNoNo Observations2069206920692069206920692069 R-squared0.6230.6190.6120.6120.6110.6120.621 Cultureisdefinedasthepercapitanumberofbookstores(column(1)),pre-recordedtapeandCDstores(column (2)),motionpictureandvideoexhibitionsestablishments(column(3)),librariesandarchives(column(4)),theaters (column(5))andmuseums(column(6))andasasthetotalnumberofthesesixtypesofestablishmentsincolumn (7). Allcontrolvariablesareincluded.Robuststandarderrorsinparentheses; ***Significantatthe1percentlevel,**5percentlevel,*10percentlevel

Table1.6:Alternativemeasure:accesstoculturalgoodsandservices(withfixed-effects) Accesstoculture CommercialNon-commercialAll BookstoresMusicstoresVideostoresLibrariesTheatersMuseumsestablishments Dependentvariable:Rents Culture-0.047***-0.008**-0.003-0.003-0.002-0.001-0.100*** (0.010)(0.003)(0.006)(0.002)(0.002)(0.003)(0.014) ControlsYesYesYesYesYesYesYes CityFixedEffectsYesYesYesYesYesYesYes Observations2072207220722072207220722072 R-squared0.6130.6060.6030.6040.6030.6010.620 Dependentvariable:Wages Culture-0.039***-0.004*-0.002-0.002-0.002-0.001-0.079*** (0.007)(0.002)(0.005)(0.001)(0.002)(0.002)(0.010) ControlsYesYesYesYesYesYesYes CityFixedEffectsYesYesYesYesYesYesYes Observations2069206920692069206920692069 R-squared0.7140.7010.7000.7000.7000.6960.722 Cultureisdefinedasthepercapitanumberofbookstores(column(1)),pre-recordedtapeandCDstores(column (2)),motionpictureandvideoexhibitionsestablishments(column(3)),librariesandarchives(column(4)),theaters (column(5))andmuseums(column(6))andasasthetotalnumberofthesesixtypesofestablishmentsincolumn (7). Allcontrolvariablesareincluded.Robuststandarderrorsinparentheses; ***Significantatthe1percentlevel,**5percentlevel,*10percentlevel

Correlation between errors across equations

The Roback (1982) model is made of a combination of two linear equations using similar explanatory variables but different sets of dependent variables. It is nevertheless likely that wages and rents in a city respond to common shocks. I take into account this interde-pendency across equations using a seemingly unrelated regression (SUR) technique. This technique accounts for the potential contemporaneous correlation between disturbances across equations. Therefore, it increases the efficiency of the estimates. The estimated coefficients are reported in Table 1.7. Columns (1) and (2) are simple cross-section es-timates while column (3) and (4) apply the SUR method to the within transformation of the model. When comparing these results to the baseline estimates provided in Ta-bles 1.3 and 1.4, we observe that the magnitude of the coefficients decreases (apart from the coefficient on wages in the cross-section analysis). When eliminating the influence of unobserved city characteristics in columns (3) and (4), the elasticities are quite small at 0.008 for rents and 0.004 for wages. The estimates remain significant only at the levels of 5 and 10% respectively. When we take into account the contemporaneous correlation between equations, the effect of culture on city attractiveness is lower even if culture still positively affects the livability and the business environment of the area.

Concentration of cultural employment

When trying to evaluate the influence of the cultural sector on a city’s attractiveness, it is important to identify the mechanism underlying this relationship – or more specifically the absence of link that is observed when implementing more demanding estimation tech-niques than simple correlations. To this aim, I distinguish in this section the influence of culture employment per se from the effect of a specialization in a few number of cultural activities and from deviations in the specialization of cities with respect to the average American city.

Cultural goods and services are particularly heterogeneous (Scott, 2000) and so are cultural occupations. Therefore, we might improve the analysis by looking at the special-ization of cities within cultural activities. If there are externalities associated with cultural diversity, a city characterized by an equal distribution of its workers among cultural oc-cupations may benefit more from these externalities than a city that is fully specialized in one activity. Conversely, there may be agglomeration economies from the specialization in a specific cultural occupation. To account for this dimension, I compute an Herfindahl index of concentration of cultural employment for each city defined as:

Herf indahlct=

withEmpcitbeing the number of persons employed in the cultural occupationiandEmpct the total number of cultural workers in citycat timet. Therefore, this index ranges from 0 – if cultural employment in the city is perfectly distributed along occupations – to 1 if the city is fully specialized in one cultural occupation. I include this variable in the baseline estimations in Tables 1.8 and 1.9.

Table 1.7: Seemingly Unrelated Regressions - cultural employment Amusement and recreation 0.077*** -0.001 -0.067*** -0.049***

(0.012) (0.009) (0.016) (0.010) Food and Drinking places 0.039* -0.022 0.378*** 0.210***

(0.021) (0.016) (0.036) (0.022)

Culture is defined as the share of cultural workers in total labor force.

Robust standard errors in parentheses;

*** Significant at the 1 percent level, ** 5 percent level, * 10 percent level

Table1.8:Concentrationindexandlocationquotients-Rentequation (1)(2)(3)(4)(5)(6)(7)(8)(9) OLSOLSIVOLSOLSIVOLSOLSIV Culture0.018**-0.012*0.028 (0.007)(0.007)(0.077) LocationQuotient-0.000-0.0000.041-0.001-0.035***0.028 (0.007)(0.005)(0.063)(0.009)(0.008)(0.078) Concentrationindex-0.0050.021***0.0010.0020.027***0.006 (0.005)(0.006)(0.039)(0.005)(0.005)(0.026) Education0.169***0.069**0.073***0.185***0.061**0.070**0.184***0.065**0.075*** (0.013)(0.027)(0.027)(0.012)(0.027)(0.030)(0.013)(0.027)(0.029) Migration0.082***0.035***0.034***0.081***0.034***0.035***0.082***0.036***0.034*** (0.005)(0.009)(0.009)(0.005)(0.008)(0.008)(0.005)(0.008)(0.009) Racialcomposition0.042***-0.061***-0.062***0.039***-0.064***-0.063***0.042***-0.061***-0.062*** (0.007)(0.010)(0.010)(0.007)(0.010)(0.010)(0.007)(0.010)(0.010) Unemployment0.098***0.087***0.086***0.101***0.090***0.090***0.098***0.083***0.089*** (0.007)(0.005)(0.005)(0.007)(0.005)(0.005)(0.007)(0.005)(0.009) Density0.046***0.935***0.922***0.048***0.979***0.953***0.048***0.920***0.940*** (0.005)(0.111)(0.100)(0.004)(0.116)(0.102)(0.005)(0.110)(0.099) Servicesector0.060***0.040***0.040***0.060***0.039***0.040***0.061***0.039***0.040*** (0.010)(0.007)(0.005)(0.010)(0.007)(0.006)(0.010)(0.006)(0.006) Violencerate-0.032***0.0040.004-0.029***0.0050.007-0.030***0.0030.005 (0.007)(0.012)(0.010)(0.007)(0.012)(0.011)(0.007)(0.011)(0.011) Amusementandrecreation0.074***-0.066**-0.064***0.072***-0.074***-0.070***0.071***-0.068***-0.063*** (0.013)(0.026)(0.020)(0.013)(0.026)(0.020)(0.013)(0.026)(0.021) FoodandDrinkingplaces0.043**0.390***0.378***0.041*0.365***0.357***0.047**0.387***0.385*** (0.021)(0.056)(0.050)(0.021)(0.054)(0.046)(0.021)(0.056)(0.045) Publicschools0.171***0.173***0.171*** (0.013)(0.012)(0.013) Humidity-0.017-0.020**-0.018* (0.010)(0.010)(0.010) Temp.January0.147***0.144***0.143*** (0.011)(0.010)(0.011) Temp.July-1.012***-1.016***-1.016*** (0.060)(0.059)(0.060) Sunlight0.192***0.191***0.194*** (0.012)(0.012)(0.012) Observations194919491943198719871982194919491943 R-squared0.7540.6070.5950.7510.6000.5830.7540.6130.591 CityFixedEffectsYesYesYesYesYesYesYesYesYes Kleibergen-PaapWeakInstr.6.9958.0256.364 UnderidentificationKP-LM0.02570.009180.0215 ***Significantatthe1percentlevel,**5percentlevel,*10percentlevel.Robuststandarderrorsinparentheses.

Table1.9:Concentrationindexandlocationquotients-Wageequation (1)(2)(3)(4)(5)(6)(7)(8)(9) OLSOLSIVOLSOLSIVOLSOLSIV Culture0.010*-0.006-0.028 (0.006)(0.005)(0.049) LocationQuotient0.007-0.001-0.0160.001-0.019***-0.027 (0.005)(0.003)(0.037)(0.007)(0.005)(0.048) Concentrationindex0.0020.010***0.0210.0050.014***0.016 (0.004)(0.004)(0.025)(0.003)(0.003)(0.016) Education0.150***0.039**0.037**0.154***0.038**0.034**0.158***0.037**0.035** (0.011)(0.016)(0.016)(0.010)(0.016)(0.017)(0.011)(0.016)(0.017) Migration0.009**0.024***0.025***0.010**0.023***0.023***0.009**0.025***0.025*** (0.004)(0.007)(0.006)(0.004)(0.006)(0.006)(0.004)(0.007)(0.006) Racialcomposition0.032***-0.052***-0.052***0.031***-0.053***-0.053***0.032***-0.052***-0.051*** (0.005)(0.007)(0.006)(0.005)(0.007)(0.007)(0.005)(0.007)(0.006) Unemployment0.074***0.061***0.062***0.077***0.062***0.062***0.075***0.059***0.058*** (0.005)(0.004)(0.004)(0.005)(0.004)(0.003)(0.005)(0.004)(0.005) Density0.042***0.875***0.882***0.041***0.891***0.900***0.043***0.867***0.864*** (0.003)(0.095)(0.077)(0.003)(0.092)(0.075)(0.003)(0.094)(0.082) Servicesector0.028***0.022***0.023***0.028***0.022***0.021***0.029***0.022***0.022*** (0.006)(0.005)(0.004)(0.006)(0.005)(0.004)(0.006)(0.005)(0.004) Violencerate-0.0020.0020.002-0.0010.0020.001-0.0010.0020.001 (0.005)(0.008)(0.006)(0.005)(0.008)(0.007)(0.005)(0.008)(0.007) Amusementandrecreation-0.001-0.050***-0.051***-0.002-0.054***-0.056***-0.002-0.051***-0.051*** (0.009)(0.017)(0.014)(0.009)(0.017)(0.014)(0.009)(0.017)(0.014) FoodandDrinkingplaces-0.0220.212***0.219***-0.026*0.205***0.208***-0.0200.211***0.211*** (0.016)(0.034)(0.034)(0.016)(0.034)(0.031)(0.016)(0.034)(0.030) Publicschools0.074***0.077***0.074*** (0.009)(0.008)(0.009) Humidity-0.031***-0.029***-0.032*** (0.008)(0.008)(0.008) Temp.January-0.041***-0.043***-0.043*** (0.007)(0.007)(0.007) Temp.July-0.526***-0.521***-0.527*** (0.044)(0.044)(0.044) Sunlight-0.002-0.002-0.001 (0.009)(0.009)(0.009) Observations194719471941198519851980194719471941 R-squared0.6140.7030.6950.6130.7010.6960.6130.7060.705 CityFixedEffectsYesYesYesYesYesYesYesYesYes Kleibergen-PaapWeakInstr.6.9478.0106.302 UnderidentificationKP-LM0.02620.009250.0222 ***Significantatthe1percentlevel,**5percentlevel,*10percentlevel.Robuststandarderrorsinparentheses.

We see in columns (1) that including this variable reinforces the influence of culture on rents but weakens its influence on wages. The coefficients associated with the concen-tration index are not statistically significant in the OLS estimations. In column (2), I add city fixed effects. Interestingly, the coefficient on culture decreases and becomes negative in both equations: when controlling for unobserved and time invariant city characteris-tics, I find that the relative size of the cultural sector is negatively associated with factor prices. However, when controlling for the size of the cultural sector, being specialized in one or a few number of cultural occupations is positively associated with both factor prices. In column (3), I control for endogeneity of culture through instrumental variables using the same instrument as in the baseline regression (the amount of federal grants per capita). The coefficients on culture and the concentration index are both insignificant in all regressions. In contrast, estimates on control variables remain very similar to the ones found in the baseline regressions. It seems then that cities that have a high share of workers devoted to specific cultural activities do not attract more firms or residents.

The positive coefficients on the Herfindahl index displayed in columns (2) emphasize the gains that are traditionally associated with specialization rather than a proper effect of culture.

In columns (4) to (6), I replace the main variable of interest – the share of cultural employment – by a location quotient. The location quotient compares the specialization of each MSA in cultural occupations with the national counterpart. This variable is defined as:

LQcultct = Empcultct /Empct Empcultt /Empt

where Empcultct is the cultural employment of city c at time t. Empct is the value of total employment in city c at time t, Empcultt the cultural employment of all U.S. cities (computed by aggregating cultural employment of the whole sample of U.S. cities) and Emptthe total U.S. labor force. The main difference with the cultural employment share is that location quotients take into account the national average or national trend to estimate the relative specialization of cities.

Columns (4) in both tables replicate the simple OLS estimation on the cross-section of cities, columns (5) use the panel dimension of the data by including city fixed-effect while columns (6) correct for endogeneity. In all specifications, the coefficient on the location quotient is not statistically different from zero meaning that when we take into account the evolution of the average level of specialization of all American cities, variations in cultural employment across cities do not capitalize into factor price differences.

Finally, in the last three columns of Tables 1.8 and 1.9, I combine the location quotient and the Herfindahl index of concentration as explanatory variables. The simple OLS estimates reported in column (7) show that any of these two variables seem to affect factor prices. Estimations with city fixed-effects provide interesting results as the coefficients on the location quotients are negative while concentration is positively correlated with factor prices. This finding is consistent with the results found in columns (2): culture per se seems to be negatively valued by firms but the specialization in a few number of cultural occupations can be considered as a production amenity as it is positively correlated with factor prices. Consistent with columns (3) or (6), the IV estimates show that neither the location quotient nor the specialization are correlated with factor prices when correcting for endogeneity biases. The Kleinbergen-Paap statistics show that the F-statistics are in all cases above the 20% critical size. Overall, the main implication of these robustness

checks is that the positive effect of culture is easily altered when implementing more demanding specifications or when trying to identify the exact mechanism underlying the effect of culture on city attractiveness.

Employment and population growth

Following Glaeser et al. (2001) and Shapiro (2006), I estimate the model in differences by taking the annual change in the log of employment and population as dependent variables.

The estimated model is given by:

ln(Empct) =β0+β1·∆ln(Sct) +β2·ln(Zct−1) +β3·ln(Xc) +γc+ct

where ∆ ln(Empct) stands for the annual change in the logarithm of total employment in city cbetweent−1 and tand ∆ ln(Sct) is the annual change in the cultural employment share. I control for the initial state of the city by including the lagged value of all control variables at t−1. Results of these estimations are provided in Table 1.10. For the sake of clarity, I do not report the estimated coefficients for the control variables.

We see in Table 1.10 that changes in cultural employment significantly affect employ-ment density only in the simple OLS estimations and in the rent regressions. Otherwise, culture does not significantly affect employment or population growth: on average, cities that face an increase in their cultural employment share do not experience higher employ-ment or population growth. I also impleemploy-ment the IV strategy for this specification. To instrument for the change in cultural employment betweent−1 andtin cityc, I compute the change in the total amount of grants received in the city between these two years.

The tests for under-identification and weak instruments do not indicate the existence of problems at the usual confidence levels. The results of the IV estimations in column (3) show that variations in the cultural environment are not associated with changes in employment or population. Including the variation in the Henfindahl index in the last column provides the same results but the statistical tests that assess the validity of the instrument are less optimistic. Hence, we may have more doubts on the reliability of these last estimated results.

Overall, all the results go in the same direction: simple correlations between culture and factor prices actually reveal the existence of a strong and positive relationship be-tween cultural environment and city attractiveness. However, controlling for (observable or unobservable) city characteristics or implementing other specifications – for instance by looking at employment and population growth, by exploring the mechanism under-lying this role of culture or by taking into account the correlation across equations – unambiguously weaken the estimated impact of culture. Then, correcting for endogeneity issues that are very likely to affect the estimated relationships strongly alter the result.

Eventually in all IV regressions, the estimated effect of culture becomes negligible. These findings systematically support the idea that simple correlations or naive estimations are actually marred by omitted variable biases, measurement problems and reverse causality issues.

Table 1.10: Employment and population growth

Dependent variable:Employment (1) (2) (3) (4)

OLS OLS IV IV

∆ Culture -0.005*** -0.003* 0.059 0.091 (0.002) (0.002) (0.049) (0.079)

∆ Herfindahl 0.083

(0.068)

City Fixed Effects Yes Yes Yes Yes

Observations 1912 1912 1902 1902

Kleibergen-Paap Weak Instr. 9.263 6.337

Underidentification KP-LM 0.00737 0.0185

Dependent variable:Population (1) (2) (3) (4)

OLS OLS IV IV

∆ Culture 0.001 0.001 -0.009 -0.014 (0.001) (0.001) (0.012) (0.018)

∆ Herfindahl -0.012

(0.005)

City Fixed Effects Yes Yes Yes Yes

Observations 1912 1912 1902 1902

Kleibergen-Paap Weak Instr. 9.263 6.337

Underidentification KP-LM 0.00737 0.0185

Culture is defined as the share of cultural workers in total labor force.

Robust standard errors in parentheses.

*** Significant at the 1 percent level, ** 5 percent level, * 10 percent level

Dans le document Essays on location choice: agglomeration, amenities and housing (Page 38-49)