In 1953, Carl Iver Hovland proposed the S-O-R (Stimulus, Organism, Response) theory, which was developed from communication and psychology. According to this theory, the content of a stimulus message influences a person's response. The message can be accepted or rejected depending on its appeal to the recipient. If the message is well understood, it will cause a change in attitude. The better the quality of the product being communicated, the easier it is for the stimulus to be accepted and build trust in the product. As a result, the organism or recipient will be more motivated to attract consumers' attention to the product or service being offered. This theory states that behavioural change is influenced by the interaction between the quality of the stimulus and the organism, where the quality of communication is the key to its success.(Suryadi et al., 2023)

A purchasing decision is an action that leads to a purchase and is ultimately followed by post-purchase behaviour. What is meant by action here is the process of recognising the need and desire for a product, assessing available resources, determining the purpose of the purchase, and considering various alternatives. In order for a purchasing decision to be made correctly, a person

needs to have reasons and objectives that underlie that choice (Puirih et al., 2020).

Social media refers to websites or applications that allow users to create and share content while interacting with other users Hudson (2020). In the past, marketing products or services was mostly done through offline methods. On the other hand, in this era of rapid technological and internet development, sellers and companies are required to adapt by switching to online sales. Now, more and more people are realising that sales through social media or online methods are more effective and efficient than offline methods (Bate’, 2019).

Elektronik Word of Mouth (E-WOM) is a form of online communication where consumers exchange opinions or reviews about products or services, both positive and negative. E-WOM is very important for marketing in today's technological era and can be conveyed through various internet platforms such as social media or product review sites. E-WOM has become very important and can even serve as a reference. Consumers are more motivated to buy goods or services if the reviews are more positive and favourable. (Amin et al., 2021).

There is another theory presented by Arianti et al. (2020), Product quality is related to the product's performance, which includes overall aspects, accuracy, durability, ease of repair, operational sustainability, and other aspects related to the product. Therefore, product quality is key to how good the product is and must be able to provide product satisfaction to consumers, and is expected to exceed competitors or at least be comparable to competing products.

Individuals who have made purchases at Donlight Donut Shop are the respondents of this research. A non-probability sampling method was used in this research. In this study, questionnaires were distributed over a period of three weeks, with the aim of obtaining 110 respondents. During that time, 110 respondents completed the questionnaire. Therefore, 110 respondents were eligible for analysis.

Based on the results of the respondent description analysis, the dominant factors in visiting and making purchases at Donlight based on gender, age, and occupation were 56 people (51%) women, then 85 people (77%) in the 18-25 age group, and 52 people (47%) were students.

The results of the descriptive analysis show that the highest respondent responses were for the social media variable, with an average value of 4.74 and a lowest value of 4.26. followed by the highest score for the e-WOM variable at 4.91 and the lowest at 4.60, the highest score for the product quality variable at 4.70 and the lowest at 4.23, and the highest average score was shown by the purchase decision variable, with a value of 4.79 and the lowest at 4.20.

According to Ghozali (2018), all items were declared valid in the validity test because the calculated r value for each item was higher than the table r value for each item. Therefore, the validity test requirements were met, and the data could be analysed further.

Based on the reliability test, each variable has a Cronbach's Alpha value above 0.60, so it is considered reliable. This means that the variables have met the reliability requirements and can be used in this study. (Ghozali, 2018).

The Kolmogorov-Smirnov normality test using SPSS produced a significance level of 0.489. Since this value exceeds 0.05, the data from 110 respondents can be declared normally distributed. (Ghozali,2018)

The above research results conclude that multicollinearity symptoms were not found because the tolerance values of each variable were greater than 0.10 and the VIF values were less than 10. (Ghozali, 2018).

From the test results, it is known that each variable has a significance value above 0.05, which means that no heteroscedasticity was found. Therefore, the research can proceed to the next analysis process. (Ghozali, 2018)

Y = 0.267 + 0.431X1 + 0.199X2 + 0.308X3

The constant value (α) of 0.267 indicates that if the variables of social media, e- wom, and product quality are 0 or unchanged, then the purchase decision is 0.267.

The explanation of the regression equation is as follows:

β₁ = 0.431, which means that every 1-unit increase in social media will increase purchasing decisions by 0.431 units, assuming other independent variables remain constant.

β₂ = 0.199, which indicates that every 1-unit increase in e-WOM will result in a 0.199-unit increase in purchase decisions if other variables remain unchanged.

β₃ = 0.308, which indicates that a 1-unit increase in product quality will increase the purchase decision by 0.308 units if other independent variables remain constant.

The adjusted R² value is 0.446 or 44.6%, indicating that 44.6% of the changes in the dependent variable (purchase decision) are influenced by the independent variables used in this study, namely Social Media, E-WOM, and Product Quality. In other words, this equation model can explain 44.6% of the variation in purchase decisions, while the remaining 55.4% is explained by external factors outside the variables used in this study. Additionally, based on the R-Square value of 0.462, the coefficient of determination is 46.2%. The R value of 0.679 indicates a relationship or correlation of 67.9% between the independent and dependent variables.

From the results of the Goodness of Fit test using the F test referring to the ANOVA value, it is known that the model can be considered feasible if the significance value is less than 0.05. Based on the ANOVA results, a significance value of 0.000 indicates that this model is significant and can be used in research.

This test is used to determine the effect of each independent variable (X) on the dependent variable (Y) (Ghozali, 2018). Based on the regression test results, the regression coefficient (β1) for the social media variable was 0.431 with a positive direction because β1 > 0. The calculated t-value is 4.455, which is greater than the table t-value of 1.658, and the significance level is 0.000, which is less than the significance level of 0.05 (α < 0.05). Thus, the results indicate that social media has a positive and significant influence on purchasing decisions. Therefore, the first hypothesis (H1), which states that social media influences purchasing decisions, can be accepted.

The regression test results show that the regression coefficient (β2) value for the electronic word of mouth (e-WOM) variable is 0.199 with a positive direction because β2 > 0. The calculated t-value of 2.011 is greater than the table t-value of 1.658, and the significance level is 0.047, which is smaller than the significance level of 0.05 (α < 0.05). Thus, the positive coefficient value and the significant t-test result indicate that e-WOM has a positive and significant effect on purchasing decisions. Therefore, the second hypothesis (H2) is accepted.

The regression analysis results show that the regression coefficient (β3) for the product quality variable is 0.308 with a positive direction because β3 > 0. The calculated t-value of 3.261 is greater than the table t-value of 1.658, and the significance value is 0.001, which is less than the significance level of 0.05 (α < 0.05). Thus, these results indicate that product quality has a positive and significant effect on purchasing decisions. Therefore, the third hypothesis (H3) can be accepted.

Statistical analysis results show that social media has a positive and significant effect on Donlight customers' purchasing decisions. This is supported by findings that the better Donlight's social media management, the higher the

tendency for customers to make purchases. This finding aligns with the Stimulus- Organism-Response (S-O-R) concept, where social media acts as a stimulus that influences consumers (organism) in making purchasing decisions.

In addition to being a promotional tool, social media also serves to build interaction between companies and customers. Satisfaction with a product encourages consumers to provide testimonials or recommendations through social media, strengthening the role of social media in the purchasing decision- making process. In its implementation, Donlight leverages social media to connect with potential customers through the presentation of engaging, educational, and interactive content. Social media serves as an effective communication tool as it can evoke emotions and spark consumer interest in products. With the right social media strategy, consumer interest in purchasing products will continue to grow.

These results are consistent with previous research by Andhyka et al. (2024), Puirih et al. (2020), Shadrina & Sulistyanto (2022), Prasetyo et al. (2021), Riskyady & Sulistyowati (2021), as well as Ningrum et al. (2023), which states that social media has a positive and significant influence on purchasing decisions. Thus, it can be concluded that social media is one of the main factors that positively and significantly influences Donlight consumers' purchasing decisions.

The results of statistical analysis indicate that the second hypothesis (H2) is accepted, which means that E-WOM has a positive and significant effect on Donlight customers' purchasing decisions. This finding is reinforced by the analysis results showing that E-WOM is more effective than conventional word- of-mouth (WOM) communication. Through advancements in digital technology, E-WOM can disseminate product information more quickly and widely. This finding aligns with the Stimulus-Organism-Response (S-O-R) theory, where E- WOM acts as a stimulus influencing consumers in making purchasing decisions. With E-WOM, consumers not only obtain information from their surroundings but can also access other users' experiences from various sources, thereby increasing trust and encouraging purchasing decisions.

The results of this study are in line with the findings of previous studies by Rahmadani et al. (2024), Waringga et al. (2023), Nyoko & Semuel (2021),Abdurrahman & Ayuningsih (2020), as well as Inayati et al. (2022), which also states that E-WOM has a positive and significant effect on purchasing decisions. Thus, it can be concluded that E-WOM is one of the effective marketing communication strategies for Donlight in increasing consumer purchasing decisions.

Based on statistical results, the third hypothesis (H3) was accepted, which means that product quality has a positive and significant effect on Donlight consumers' purchasing decisions. This finding is supported by an analysis showing that product quality is closely related to its ability to meet good quality standards. Factors such as product performance, functional accuracy, durability,

ease of maintenance, and consistency are the main determinants of product quality. Product quality is an important element in shaping customer satisfaction levels. High-quality products are expected not only to meet customer expectations but also to compete with or even surpass the quality of competitors' products. Satisfaction with high-quality products encourages customers to make repeat purchases or recommend them to others. This finding aligns with the Stimulus-Organism-Response (S-O-R) theory, where product quality acts as a stimulus that influences customer response. When customers receive products that meet their expectations, it evokes feelings of satisfaction and joy, and encourages the desire to make repeat purchases. In the long term, customers may become loyal or recommend the product to others.

The results of this study are consistent with previous studies conducted by Lutfila Roibafi et al. (2022), Juwita (2021),Grandhis (2022),Mulia & Risnawati (2020), Shah et al. (2023), Sunarsi (2020), as well as Mappatompo & Rizal (2023), which also shows that product quality has a positive and significant effect on purchasing decisions. However, there are other research results by Sintya et al. (2024) dan Wijiastuti et al. (2024) which showed different results. Thus, it can be concluded that product quality plays an important role in influencing Donlight consumers' purchasing decisions, particularly in building customer satisfaction and loyalty.