This study aims to analyze the significant influence of product quality, service quality, and promotion on purchasing decisions. The data used in this study are quantitative and qualitative. The data sources used are primary and secondary data. The sample in this study was 100 consumers of Kopi Tanjung CV Dimensi Tiga. The data collection technique in this study used a questionnaire and literature study. The sampling technique used in this study is purposive sampling. The research instrument test used validity and reliability tests. The classical assumption test used: multicollinearity, autocorrelation, heteroscedasticity, and normality tests. The data analysis technique used multiple linear regression tests, t-tests, F-tests, and R2 tests. Validity and reliability test results indicate that all statement items regarding product quality, service quality, promotion, and purchasing decisions are valid (p-value < 0.05) and reliable (Cronbach’s alpha > 0.60). Classical assumption test results show that all variables passed the tests for multicollinearity, autocorrelation, and heteroscedasticity, and that the residuals are normally distributed. Regression analysis yielded the equation Y = 2.101 + 0.232 X1 + 0.483 X2 + 0.253 X3. The t-test results show a p-value (significance) of < 0.05; thus, product quality, service quality, and promotion have a significant effect on purchasing decisions. F-test results indicate that the regression model used in this study is appropriate. The R² test result shows that the independent variables contribute 79.8% to the dependent variable, while the remaining 20.2% is explained by variables outside the model—such as price and brand image—that were not included in this study.
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