Descriptive analyses

Figure 6 depicts the average share endowment contributed to rubber agroforestry by treatment and payment level for both hypothetical and incentivized decisions.

Figure 6: Average share endowment contributed to conservation by treatment and pay-ment level (for both hypothetical and incentivized decisions).

In the first hypothetical decision, where participants did not receive a hypothetical in-centive for the practice of rubber agroforestry, on average around one third of the en-dowment (non-framed 37.8, framed 34.5) is contributed to conservation. As expected, the average share endowment allocated to conservation in the first hypothetical deci-sion does not significantly differ between the treatments (Wilcoxon rank sum test; p-value 0.582). To investigate whether the framing even works in a hypothetical setting, in the second decision, we introduced a hypothetical incentive for the practice of rubber agroforestry. Indeed, in the framed treatment, the average share endowment assigned to conservation significantly increases by 0.082 compared to the first hypothetical deci-sion (Wilcoxon signed-rank test; p-value 0.000). In the non-framed treatment, the aver-age conservation behaviour (compared to the first hypothetical decision) increases only by 0.019 (Wilcoxon signed-rank test; p-value 0.000). Comparing the differences in the increase in conservation behaviour between non-framed and framed treatment reveals that the increase in conservation is significantly higher (Wilcoxon rank sum test;

p-37,8 39,7

35,2 35,8

41,9 34,5

42,8 43,6 46,3 50

0 10 20 30 40 50 60

No (NI) Medium (NI) No (I) Low (I) High (I) share endowment contributed to conservation

Non-framed Framed

value 0.019) under the framed treatment than under the non-framed treatment. This indicates that the framing produces a crowding effect even in a hypothetical setting.

Turning to the incentivized decisions, we compare the first incentivized decision, where no monetary incentive for the cultivation of rubber was paid with the first hypothetical decision. Assuming a contingent restart effect or an effect due to the introduction of the non-hypothetical setting, we expect that differences in conservation behaviour between the decisions do not significantly differ between the treatments. In the non-framed treatment group, the average contribution to conservation does not significantly differ between the decisions (Wilcoxon signed-rank test; p-value 0.4945). However, in the framed treatment group the average contribution is significantly higher in the first in-centivized decision than in the first hypothetical decision (Wilcoxon signed-rank test; p-value 0.0024), suggesting that the framing effect induced by the hypothetical incentive persists even after its removal. Comparing the differences in conservation behaviour between the first decisions across treatments reveals that the difference is significantly higher under the framed treatment than under the non-framed treatment (Wilcoxon rank sum test; p-value 0.002).

To explore the effects resulting from the PES framing, we compare the average change in conservation behaviour in the second and third incentivized decisions (compared to the first hypothetical decision) across treatments. Since the first incentivized decision under the framed treatment is biased towards conservation due to the framing effect in the hypothetical setting, we use the first hypothetical decision as our baseline. We think that it is plausible to argue that potential restart effects and effects due to the change in the incentivized setting do not differ between the treatment group and hence do not target our main research question. Irrespective of the amount of the monetary incen-tive, in the non-framed treatment the average endowment share contributed to conser-vation does not significantly increase (Wilcoxon signed-rank test; p-value H0: NI-Low 0.6958, H0:NI-High 0.2256). In contrast, the introduction of an incentive explicitly framed as PES significantly increases the average endowment share contributed to rub-ber agroforestry for both low and high payment amounts (Wilcoxon signed-rank test H0:NI=low 0.0000; H0:NI=high 0.0000). To test H1—that the framing effect crowds in conservation behaviour—we investigate the differences in the change in conservation

behaviour across treatments. Results confirm that the change in the average endow-ment share contributed to rubber agroforestry is significantly higher among partici-pants in the framed treatment group than among those in the non-framed treatment group irrespective of the payment amount (Wilcoxon rank sum test; H0: Non framed-framed for Δ NI-Low 0.0001; Δ NI-High 0.0008).

To address H2, which states that the crowding effect does not appear for participants with very weak or no preferences for the practice of rubber agroforestry, Table 5 de-picts the share of participants with zero investment in rubber agroforestry by payment amount and treatment for hypothetical and incentivized decisions.

Table 5: Share participants with zero investment in rubber agroforestry by payment level and treatment for hypothetical and incentivized decisions

Non-Framed Framed H0: Non

Wilcoxon rank sum test for comparison across treatments; Wilcoxon signed-rank test for comparison within treatment

In the first hypothetical decision around one fourth of all participants fully specialize in oil palm. Given a non-framed incentive, the proportion of participants that do zero in-vestment in rubber agroforestry does not significantly change. In contrast, under the framed incentive, the proportion of participants that do zero investment significantly decreases. Given low payment levels, the change in the proportion is significantly differ-ent between the treatmdiffer-ents. These findings do not support the notion (H2) that the con-servation behaviour of participants with no preferences for rubber agroforestry is unaf-fected by the framing effect.

3.7.2 Econometric analyses