The influence of trust on the online purchase decisions with buying interest on the social networking site Instagram: case study of online shop users on Instagram A influência da confiança nas decisões de compra online com interesse de compra no site de rede social Instagram: estudo de caso de usuários de loja online no Instagram La influencia de la confianza en las decisiones de compra en línea con interés de compra

Background of this study is the internet technology improvement through social media Instagram which has huge potential on online selling. It found the fraud case that occurs through Instagram it is causes purchasing decreases. Price, information quality and purchase interest as the main factors which causes someone to shopping via online. The research cases study implementing to an online shop which is engaged in the food sector. This research used 5 variables such as consumer trust, price, information quality as an independent variable, online purchasing decisions as a dependent variable, with purchasing interest as variable intervening. This research used SmartPLS 3.0. The research method that used is qualitative approach, the associative type research, data collection technique used questionnaire, and the type of data that used is primary data which obtained of 95 respondents which already shopping via online in Instagram. The result showed that consumer trust, price, and information quality on purchasing interest with consumer trust and purchasing interest on the Research, Society and Development, v. 9, n. 10, e8669109119, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.9119 2 purchasing decision which has positive effect and significant, while price and information quality has no effect on the purchasing decision. Purchase interest is able to mediate between consumer confidence in purchasing decisions, the price of the purchase decision, and the intention of buying is not able to mediate the quality of the information on the purchase decision.

fraude que se produce a través de Instagram provoca una disminución de las compras. El precio, la calidad de la información y el interés de compra son los principales factores que llevan a alguien a comprar a través de Internet. El estudio de casos de investigación se implementa en una tienda online que se dedica al sector de la alimentación. Esta investigación utilizó 5 variables como la confianza del consumidor, el precio, la calidad de la información como variable independiente, las decisiones de compra online como variable dependiente, con el interés de compra como variable interviniente. Esta investigación utilizó SmartPLS i3.0. El método de investigación que se utilizó es el enfoque cualitativo, la investigación de tipo asociativo, la técnica de recopilación de datos utilizada por cuestionario, y el tipo de datos que se utilizó son los datos primarios que se obtuvieron de 95 encuestados que ya estaban comprando vía online en Instagram. El resultado mostró que la confianza del consumidor, el precio y la calidad de la información sobre el interés de compra con la confianza del consumidor y el interés de compra sobre la decisión de compra tiene un efecto positivo y significativo, mientras que el precio y la calidad de la información no tiene ningún efecto sobre la decisión de compra. El interés de compra puede mediar entre la confianza del consumidor en las decisiones de compra, el precio de la decisión de compra y la intención de compra no puede mediar la calidad de la información sobre la decisión de compra.

Introduction
The development of internet technology has changed various aspects of life including consumer behavior. The changes in how to obtained information, the need to make decisions in a fast manner without being ties of space and time, and the need to actualize in the cyberspace have an indirect or direct impacts on the consumer's ideal behaviors in buying and consuming products (Wong, 2017).
One of the social media that is currently widely used by the public is Instagram. Based on data from internet users in Indonesia, social media Instagram has potential to make it easier for producers to sell online, on the other hand, and for consumers to obtain various product information that they want to buy (Sunarto, 2018).
There are many fraud cases occurred through Instagram, causing the purchase level to decrease. The decrease in the purchasing level via Instagram because of the people's idea Development, v. 9, n. 10, e8669109119, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.9119 4 those are not responsible. Irresponsible people are used media to reap personal gain and harm others. must be careful in making online purchase transactions via Instagram (Sriyanto & Kuncoro, 2019).
Moreover, the online store ability itself which given the service also can influenced the consumer trust. The trust which already exists in someone else will generate a sense of consumer buying interest in online stores. Those things show that interest the level higher of consumer confidence, the higher the consumer buying interest (Imam Ghozali & Latan, 2015).
The prices have the effect through the purchasing decision. The prices offered by the online shop vary according to the quality. The price is considered as one of the factors which influenced the purchasing decision. Affordability, the suitability of prices for goods, makes consumers make decisions to buy online (Widhiani & Idris, 2018).
To attract the online purchases, e-commerce must know the individual perceptions influence online purchasing decisions. Online shopping is closely related with trust to the information and transactions. Thus, it can be concluded that trust will creates if the consumer get the quality of information needed is complete or the customer has understood a purchasing system on a website (Sangadji & Sopiah, 2013).

Consumer trust
According to (Mowen & Minor, 2001) consumer trust is all the knowledge the consumer has and all the conclusions that the consumer makes, attribute, and benefits. There are the indicators such as: ability, benevolence and integrity. Research, Society and Development, v. 9, n. 10, e8669109119, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.9119

Prices
Price is one of the most flexible elements of the marketing mix, Prices can be changed faster unlike product views and distribution agreements (Kotler & Susanto, 2001). The indicator from the prices such as: Price affordability, price competitiveness, price compatibility with benefits.

Information quality
According to Park and Kim in (Brilliant & Achyar, 2014), the information quality is customer perceptions through information quality related to the product or service which served by website. Indicator of information quality as below: up to date information, help online customer in making decision, consistent, ease to understand.

Purchasing decision
The purchasing decision is the stage in the purchasing decision-making process until the consumer actually buys the product (Sangadji & Sopiah, 2013). As for the indicators of the Purchase Decision is trust in buying, as the wishes, having wishes to repurchase, considering the product quality, recommendation to other people.

Purchasing interest
According to Kotler and Keller in (Satria, 2017) Consumer purchase interest is a consumer behaviour where consumers have the desire to buy or choose a product, based on experience in choosing, use and consume or even desire a product. Indicator of the purchasing interest such as: transactional, referential, preferential, and explorative interest.

Hypothesis
Based on the background above, theoretical basis and the research purpose so it can be formulated the hypotheses as below in the Figure 1: In the Figure 1, it becomes interesting that you write a paragraph in which you say what is important for the reader to observe in it. The journal is multidisciplinary and we have readers from several different areas that often do not have "your expertise" in capturing the details that they often think they are transmitting. Do that, thank you.

Validity test
According to Chin (1998) in (I. Ghozali, 2012), a correlation can be said fulfilled the convergent validity if it has loading value as much as 0,5. Output shows that loading factor gives the value above value that suggest as much as 0,5. The indicators that used in this research have fulfilling the convergent validity, it can be seen in the Table 1 below: Source: Data processed with SmartPLS, (2020).
In the Table 2, the cross loading in the table above can be stated valid because there are loading value above 0,5. Until the indicators that used in this research has fulfilled convergent validity. In the Table 4 shows that all latent variables measured in this research have Cronbach's Alpha and Composite Reliability is greater than 0.7, so it can be said that all latent variables are reliable.
In the Table 6, it shows that T-statistics value is higher than P-value, if T-statistics value is higher than T-table value (2,16) with a level significance 5% or through P-Value α=5%, p-value=0,05. Bootstrapping process result PLS can be seen in the Table 6 below: Table 6. Total Indirect Effects.

Hypothesis 1: Consumer Confidence Affects Purchase Intention
The results of the path coefficient test between consumer trust and purchasing decisions have a parameter coefficient of 0.279 with the significance of the T-Statistics value 2.331> 1.96 and the P-value value is 0.020 <0.05. This is shows that consumer has influence and significant through purchasing interest. The research result is information qualities has Research, Society and Development, v. 9, n. 10, e8669109119, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.9119 13 not influenced through purchasing decision with purchasing interest as mediation variable.
The results of this study are in line with the research Resa dan Aulia (2018) that trust have significant influenced through purchasing interest.

Hypothesis 2: Price Affects Buying Interest
The result of the coefficient path test between price with purchasing interest have a parameter coefficient as much as 0,288 with the significance of the T-Statistics value 0,279>1,96 and P-Value is 0,29<0,05. This is shows that the price has significant positive effect through purchasing interest. The result is in line with the research of (Satria, 2017) that price has positive effect or significant through purchasing interest, where purchasing interest is higher can be formed by the by the price offered by service providers or products.

Hypothesis 3: The Quality of Information Affects Purchase Intention
The result of the coefficient path test result between price with purchasing interest have a parameter coefficient as much as 0,288 with the significance T-statistics value 0,279>1,96 and P-value is 0,029< 0,05. This is shows that price has significant positive effect through purchasing interest. Result research is in line with research of (Widhiani & Idris, 2018) that information quality has positive effect through purchasing interest.

Hypothesis 4: Consumer Confidence Influences Purchasing Decisions
The result of the coefficient path test between consumer trust with purchasing decision have a parameter coefficient of 0,204 with the significance T-Statistics value 2,318>1,96 and P-value is 0,021<0,05. This is shows that consumer trust has influence and significant through the purchasing decision. The result is in line with Florentinus and Sumarno (2015) that trust on the purchasing decision through social networking sites.

Hypothesis 5: Price Has No Effect on Purchasing Decisions
The result of the hypothesis test shows coefficient path between company size and profitability have a parameter coefficient of -0,084 with the significance T-statistics value as much as 0,918<1,96 and P-value is 0359>0,05. This is shows that price has not influenced and not significant through the purchasing decision. The results is in line with (Setyarko, 2016) that price is known to have no effect in online product purchasing decisions. The consumer perception through price of a product is not become the main focus in making decision.

Hypothesis 6: The Quality of Information Has No Effect on Purchasing Decisions
The result of the hypothesis test shows coefficients path between information quality with purchasing decision have a parameter coefficient of 0,159 with significant of T-statistics value 1,373<1,96 n P-value is 0,170>005. This is shows that information quality has not influenced and not significant through the purchasing decision. The result is in line with (Nazarudin & Pela, 2016) that information quality is not influenced on the purchasing decision.

Hypothesis 7: Purchase Intention Affects the Purchasing Decision
The result of the hypothesis test shows coefficient path between purchasing interests with purchasing decision have a parameter coefficient of 0,647 with significance of Tstatistics value 8,330<1,96 and P-value of 0,000<0,05. This shows that purchasing interest has positive significant influence on purchasing decision. The result is in line with (Rahmawati, 2018;Sriyanto & Kuncoro, 2019) where purchasing interest has positive influence and significant on the purchasing decision.

Intention as the Mediation Variable
The result of the hypothesis test shows coefficient path between consumer trust with purchasing interest have a parameter coefficient of 0,181 with the significance of the T-Statistics value 2,194>1,96 and P-value 0,029<0,05. This shows that purchasing interest is able to mediate the effect of price on purchasing decisions. This research is in line with (Kholis et al., 2018) that purchasing interest variables is intervening variables and proved feasible for consumer trust on the purchasing decision.

Hypothesis 9: Price Affects the Purchase Decision with Purchase Intention as a Mediation Variable
The result of the hypothesis test shows coefficient path between price with purchasing interest have parameter coefficient of 0,187 with T-statistics significant 2,169>1,96 and Pvalue 0,031<0,05. This shows that purchasing interest is able to mediate the effect of price on purchasing decisions. This research result is in line with (Az-Zahra et al., 2019) that purchasing interest can mediate between price on the purchasing decision.

Hypothesis 10: The Quality of Information Has No Effect on Purchasing Decisions with Purchase Intention as the Mediation Variable
It can be seen that hypothesis test result shows path coefficients between information quality with purchasing interest have parameter coefficient of 0,156 with the significance of the T-Statistics value 1,897>1,96 and P-value 0,058> 0,05. This is shows that purchasing interest is unable mediate the influence of Information Quality through purchasing decision.
This research is in line with (Yunita et al., 2016) that purchasing interest is not intervening variable which is mediate the influence of information quality on the online purchasing decision.

Conclusion
1. Consumer trust has positive effect and significant through purchasing interest in the Instagram social networking site means that consumer trust on the consumer purchasing interest shows that consumer trust level on online shop seller of Dapur Kakak is not maximal. Research, Society and Development, v. 9, n. 10, e8669109119, 2020 (CC BY 4.0