Participant retention and fieldwork profile
A total of 480 questionnaires were obtained during formal fieldwork at Longmen Grottoes. After eligibility screening and data-quality checks, 430 questionnaires were retained for analysis, giving a valid-response rate of 89.6%. The final valid sample exceeded the pre-specified minimum requirement of 400 valid questionnaires. Excluded cases included eligibility failures, failed attention checks, fast completion, straight-lining or near-invariant response patterns, duplicate responses, and other fieldwork problems. When one questionnaire met more than one exclusion condition, the earliest applicable protocol rule was used as the primary exclusion category. The screening flow from 480 raw questionnaires to 430 valid cases is shown in Figure 2.
The retained cases were distributed across the three planned public survey points. The visitor exit area contributed 139 valid cases, the public rest area outside the main visiting route contributed 146 cases, and the visitor service area near the transportation connection point contributed 145 cases. First-time visitors accounted for 55.6% of valid cases, and repeat visitors accounted for 44.4%. Organized group-tour participants accounted for 23.0%, which remained below the pre-specified monitoring boundary. The fieldwork distribution and visitor profile are shown in Table 6.
Construct distribution and measurement diagnostics
The construct scores showed sufficient dispersion for analysis. Mean scores ranged from 3.258 to 3.415, and standard deviations ranged from 0.837 to 0.892. No construct showed a strong ceiling effect based on the pre-specified dispersion checks. Perceived crowding was retained in its original direction, so a higher score indicated stronger perceived crowding rather than a more positive visitor experience.
Cronbach’s alpha ranged from 0.699 for perceived crowding to 0.812 for self-reported responsible travel behavior. All constructs met either the acceptable reliability threshold or the marginal-reliability rule. Perceived crowding was reported as marginally reliable because its alpha was slightly below 0.70. It was retained because the corrected item-total correlations met the protocol threshold and the construct was needed to represent visitor-pressure conditions at a high-traffic heritage site.
The nine-factor confirmatory factor analysis supported the planned measurement structure. The model fit indices were acceptable: χ2 (398) = 712.4, CFI = 0.932, TLI = 0.918, RMSEA = 0.043, and SRMR = 0.052. Standardized factor loadings ranged from 0.56 to 0.84. Composite reliability values ranged from 0.702 to 0.842. Average variance extracted ranged from 0.453 to 0.575, with the lowest value occurring for perceived crowding.
Discriminant-validity checks did not indicate severe construct overlap. The maximum HTMT value was 0.642, below the pre-specified review threshold. Conservation attitude, conservation willingness, and self-reported responsible travel behavior remained distinguishable in the measurement model. The first unrotated factor explained 18.7% of the total variance, below the 40% common-method screening threshold. This result was treated only as a screening result and not as evidence that common-method bias was absent. The strongest construct correlation was between conservation attitude and conservation willingness, r = 0.432, and no construct pair exceeded the 0.70 redundancy threshold. The main measurement diagnostics are summarized in Table 7. Full item-level reliability results, CFA loadings, CR, AVE, HTMT, and inter-construct correlations are provided in Supplementary Table 1, Supplementary Table 2, and Supplementary Table 3.
Model outputs and sensitivity checks
The protocol produced interpretable regression and path-model outputs without serious multicollinearity. The three regression models showed moderate explanatory power. The conservation attitude model had R2 = 0.267 and adjusted R2 = 0.224. The conservation willingness model had R2 = 0.333 and adjusted R2 = 0.292. The self-reported responsible travel behavior model had R2 = 0.275 and adjusted R2 = 0.228. These values were within the pre-specified plausible range for cross-sectional visitor-behavior data.
The path model followed the planned sequence: site-related predictors → conservation attitude → conservation willingness → self-reported responsible travel behavior. Model fit was acceptable: CFI = 0.927, TLI = 0.904, RMSEA = 0.049, and SRMR = 0.041. The core path estimates were interpretable. Conservation attitude was positively associated with conservation willingness, β = 0.276. Conservation attitude and conservation willingness were positively associated with self-reported responsible travel behavior, β = 0.232 and β = 0.271, respectively. The indirect effect from conservation attitude to self-reported responsible travel behavior through conservation willingness was 0.075, with a bootstrap 95% CI of 0.036–0.122. The full regression coefficients, path estimates, indirect effects, total effects, and model-output files are provided in Supplementary File 3, Supplementary Table 4, and Supplementary Table 5.
The regression diagnostics did not indicate serious multicollinearity. VIF values ranged from 1.012 to 1.422, below the pre-specified threshold of 3.00. Influential-case diagnostics did not justify removing cases from the primary models. Cases flagged by Cook’s distance were retained in the primary analysis and evaluated in sensitivity checks.
The sensitivity checks supported the stability of the protocol outputs. No valid questionnaire exceeded the 1,800 s completion-time threshold. After organized group-tour participants were removed, after median-based construct scoring was used, and after Cook’s-distance-flagged cases were excluded, the main coefficient directions were retained. Across sensitivity specifications, the standardized coefficient for conservation attitude → conservation willingness ranged from 0.261 to 0.290, conservation attitude → self-reported responsible travel behavior ranged from 0.198 to 0.260, and conservation willingness → self-reported responsible travel behavior ranged from 0.243 to 0.298. Complete sensitivity-check outputs are provided in Supplementary Table 6.
Summary of protocol outputs
The workflow produced a valid analytical sample above the pre-specified minimum sample requirement, with completed questionnaires distributed across all planned survey points. The retained sample included variation in visitor background and travel mode, and the organized group-tour proportion remained within the monitoring boundary. The measurement checks supported the use of construct-level scores: most constructs met the reliability threshold, perceived crowding was retained as marginally reliable, the nine-factor CFA showed acceptable fit, and discriminant-validity checks supported separation among conservation attitude, conservation willingness, and self-reported responsible travel behavior.
The model outputs were used to demonstrate that the protocol could generate analyzable and auditable visitor-behavior evidence. The regression and path-model results were interpretable, the indirect-effect test was available for the planned attitude–willingness–behavior sequence, and the sensitivity checks did not change the direction of the core associations. These results support the procedural use of the workflow for minimum-disruption heritage-site visitor surveys rather than serving as direct observational evidence of visitor behavior. The de-identified dataset, questionnaires, supporting study documents, analysis script, complete model outputs, and source data for all figures and tables have been deposited in Zenodo (DOI: https://doi.org/10.5281/zenodo.21640066).

Figure 1: Protocol workflow for the Longmen Grottoes visitor survey. The workflow shows the sequence used in this protocol, from questionnaire construction, pilot testing, public-area visitor interception, questionnaire administration, and raw-data locking to quality screening, construct scoring, measurement validation, model estimation, sensitivity checks, and study-file archiving. Please click here to view a larger version of this figure.

Figure 2: Questionnaire screening flow for the final analytical sample. The diagram shows the transition from 480 raw questionnaires to 430 valid questionnaires after eligibility screening, attention-check review, completion-time screening, straight-lining detection, duplicate-response inspection, and fieldwork-related quality checks. Exclusions are counted by primary exclusion reason when more than one warning condition is present. Please click here to view a larger version of this figure.
Table 1: Construct map and questionnaire structure for the Longmen Grottoes visitor survey. This table summarizes the construct definitions, abbreviations, item codes, number of items, scoring direction, analytical position, and source or adaptation basis used to measure visitor conservation willingness and self-reported responsible travel behavior. Full item wording is provided in Supplementary File 1. All substantive items were scored from 1 = strongly disagree to 5 = strongly agree. PC was retained in its original direction; a higher PC score indicates stronger perceived crowding. Please click here to download this Table.
Table 2: Fieldwork schedule and systematic intercept sampling plan. This table presents the formal data-collection period, public survey points, daily time windows, sampling interval, raw sample target, minimum valid sample requirement, visitor-composition monitoring ranges, suspension rules, and fieldwork-recording variables. Please click here to download this Table.
Table 3: Eligibility, attention-check, and quality-screening rules. This table presents the eligibility criteria, attention-check rules, completion-time thresholds, straight-lining rules, duplicate-response checks, exclusion codes, and retained-data decisions applied before construct scoring. Please click here to download this Table.
Table 4: Variable coding and construct-score calculation plan. This table defines the coding rules for respondent ID, demographic variables, travel-related variables, survey records, attention-check variables, Likert-scale items, construct scores, and exclusion status. All construct scores remain on the original 1–5 scale. Item-level missing-value imputation was not used because all substantive questionnaire items were required fields. Please click here to download this Table.
Table 5: Pre-specified diagnostic thresholds used before model interpretation. This table reports the thresholds for reliability, item retention, confirmatory factor analysis, discriminant validity, common-method screening, distributional checks, correlation review, multicollinearity, influential-case diagnostics, model plausibility, significance testing, and indirect-effect interpretation. CFA = confirmatory factor analysis; CFI = comparative fit index;
TLI = Tucker-Lewis index; RMSEA = root mean square error of approximation; SRMR = standardized root mean square residual; CR = composite reliability; AVE = average variance extracted; HTMT = heterotrait-monotrait ratio; VIF = variance inflation factor. Please click here to download this Table.
Table 6: Fieldwork distribution and demographic characteristics of the valid sample. This table summarizes the distribution of valid questionnaires by survey point, time window, survey period, gender, age group, education, monthly personal income, visit status, and travel mode. Percentages were calculated using the final analytical sample, n = 430. Percentages may not sum to 100.0 because of rounding. Please click here to download this Table.
Table 7: Summary of construct distribution, measurement diagnostics, model outputs, and sensitivity checks. This table summarizes construct-level descriptive statistics, Cronbach’s alpha values, CFA fit indices, composite reliability, average variance extracted, HTMT, common-method screening results, regression model fit, path-model fit, indirect-effect testing, multicollinearity diagnostics, and sensitivity-check stability. Complete item-level reliability results, CFA loadings, HTMT matrix, inter-construct correlations, regression coefficients, path estimates, indirect effects, total effects, and sensitivity-check outputs are provided in Supplementary File 3. HK = heritage knowledge; PHV = perceived heritage value; PA = place attachment; PMQ = pro-environmental message quality; PC = perceived crowding; FSW = facility and service support; CA = conservation attitude; CW = conservation willingness; RTB = self-reported responsible travel behavior. PC was retained in its original direction; higher PC indicates stronger perceived crowding. Please click here to download this Table.
Supplementary File 1: Questionnaire and consent materials. This file provides the final questionnaire, informed-consent page, eligibility-screening questions, attention-check items, questionnaire-platform display record, and pilot-review record.Please click here to download this file.
Supplementary File 2: Fieldwork and data-management records. This file provides the fieldwork-log form, role-assignment record, data-management log, exclusion-log form, and codebook structure.Please click here to download this file.
Supplementary File 3: Analysis and reproducibility materials. This file provides the de-identified analysis dataset, analysis script, sessionInfo() output, item-level reliability outputs, CFA outputs, HTMT matrix, inter-construct correlation matrix, regression outputs, path-model outputs, indirect-effect outputs, sensitivity-check outputs, complete model-output workbook, and figure/table source-data checklist.Please click here to download this file.
Supplementary Table 1: Item-level descriptive statistics and reliability outputs. All corrected item-total correlations were ≥0.30. PC = perceived crowding.Please click here to download this file.
Supplementary Table 2: Standardized CFA loadings, CR, and AVE. CFA = confirmatory factor analysis; CR = composite reliability; AVE = average variance extracted.Please click here to download this file.
Supplementary Table 3: Inter-construct correlation matrix. HK = heritage knowledge; PHV = perceived heritage value; PA = place attachment; PMQ = pro-environmental message quality; PC = perceived crowding; FSW = facility and service support; CA = conservation attitude; CW = conservation willingness; RTB = self-reported responsible travel behavior.Please click here to download this file.
Supplementary Table 4: Complete regression outputs. Controls included gender, age group, education, monthly personal income, first-time visit status, and travel mode. VIF = variance inflation factor.Please click here to download this file.
Supplementary Table 5: Path-model and indirect-effect outputs. CA = conservation attitude; CW = conservation willingness; RTB = self-reported responsible travel behavior.Please click here to download this file.
Supplementary Table 6: Sensitivity checks for the main model outputs. CA = conservation attitude; CW = conservation willingness; RTB = self-reported responsible travel behavior.Please click here to download this file.
Supplementary Table 7: Figure and table source-data checklist. Please click here to download this file.