## 3 Results  
### Threshold Effects and Values of African Swine Fever-Related News on Retail Pork Prices  
Regarding the validation of the threshold model, there should be threshold effects in the AR model, as shown in Table 2. The distribution used in the threshold effect test shown in Table 2 corresponds to the asymptotic distribution through bootstrapping, and the critical value can vary from trial to trial [17]. Therefore, the results of repeated tests were used in this study. To test for a threshold effect and estimate the threshold values in the AR model, the \"tsDyn\" package in R-software was used. The ASF-related SNS frequency was included as an exogenous variable when the coefficients and impulse response periods for each regime were estimated using the impulse response functions in STATA software. The results of the threshold effects test indicated that the AR model for retail pork prices had two threshold values based on ASF-related news frequency. These results suggested that the TAR model could be divided into three regimes based on the ASF-related news frequency as shown in Table 3. Here, instead of the actual news frequency, the difference between the frequencies for the previous date and the current date was used because the actual news frequency happened to have a unit root. The threshold values for the pork TAR model in Table 3 were estimated based on the least square value to be \(-9\) and \(8\) of the difference between the news frequencies of the previous date and those of the current date. Based on the threshold values, the TAR model could be divided into three regimes: regime 1, where the difference in the ASF-related news frequencies is less than \(-9\); regime 2, where the difference is between \(-9\) and 8; and regime 3, where the difference is greater than or equal to 8. The frequency of ASF-related news increased from regime 1 to regime 3. The coefficients of the difference between the retail prices of the previous date and those of the current date showed negative trends when they were statistically significant, indicating that the retail price difference of the past may have the opposite effect on the retail price difference in the present. When the retail price difference of the past showed an increasing trend, the one for the present had a decreasing trend to return to equilibrium. Regarding the effect on retail pork prices in 2019, the coefficients of the ASF-related SNS frequencies showed a statistically significant positive relationship in regime 1, where the difference in the ASF-related news frequency was less than \(-9\), as shown in Table 4. These results can be interpreted as meaning that when ASF-related SNS frequency increase compared to that on the previous day, the retail pork price increased by 1.1666 Korean won (KRW). In general, the frequencies of news and the SNS tended to migrate together. Due to the nature of the news, there was a tendency for reports to be more negative than positive. In regime 1, where the frequency of news decreased compared to the previous day, ASF-related news also decreased, though it may have contained negative content. In this context, when the SNS frequency increased in the regime where the news frequency decreased, it was highly likely that the SNS posts contained positive information about ASF, such as the end of the epidemic. As in regime 1, the coefficients of the ASF-related SNS frequencies in regime 2 showed a positive relationship. On the other hand, the coefficients showed a negative relationship on retail pork prices in regime 3, where the difference in the ASF-related news frequency was greater than or equal to 8. Because the news was mainly negative, as mentioned above, regime 3, where the ASF-related news frequency increased, was more likely to have a high proportion of negative news, such as an ASF outbreak. Accordingly, ASF-related SNS posts were also likely to contain negative content that could cause a decrease in consumer demand for pork, leading to a drop in retail prices. However, this speculation requires further study.