Hello,
I have experimental data about 99 consumers (called IDconsumer) tasting and evaluating 5 products, on seven consecutive steps. Each consumer notes each of the five products on each of the seven steps, with new information on the products they are provided with between each two steps, potentially changing each consumer notes on the products.
I’d like to measure the effects of the products, of the steps (i.e. the information given between steps) and of the combined effects products x steps, and I’m a bit confused on the commands to use.
As observations are not independent (same consumers note each product seven times), I can’t run a simple ANOVA (‘anova note step##product’). But I’m hesitating on using either repeated measures ANOVA or multilevel mixed-effects linear regression. And on both models, I’m hesitating on the form I should put them.
For the repeated-measures ANOVA, I’ve written it ‘anova note i.step/IDconsumer|step i.product product#step, repeated(product)’ but I’m not sure about the between-subjects error term and nested variables.
For the mixed model, I’ve written it ‘mixed note i.step##i.product ||IDconsumer:
Again, as notes are given by the same consumers, I’m wondering if I should add the option for autoregressive residuals…
Estimation results are the following:
pwcompare command gives slightly different results too about the significant differences between steps and products.
Can you advise me about the most appropriate tests to conduct with my data?
Thank you very much.
I have experimental data about 99 consumers (called IDconsumer) tasting and evaluating 5 products, on seven consecutive steps. Each consumer notes each of the five products on each of the seven steps, with new information on the products they are provided with between each two steps, potentially changing each consumer notes on the products.
I’d like to measure the effects of the products, of the steps (i.e. the information given between steps) and of the combined effects products x steps, and I’m a bit confused on the commands to use.
As observations are not independent (same consumers note each product seven times), I can’t run a simple ANOVA (‘anova note step##product’). But I’m hesitating on using either repeated measures ANOVA or multilevel mixed-effects linear regression. And on both models, I’m hesitating on the form I should put them.
For the repeated-measures ANOVA, I’ve written it ‘anova note i.step/IDconsumer|step i.product product#step, repeated(product)’ but I’m not sure about the between-subjects error term and nested variables.
For the mixed model, I’ve written it ‘mixed note i.step##i.product ||IDconsumer:
Again, as notes are given by the same consumers, I’m wondering if I should add the option for autoregressive residuals…
Estimation results are the following:
Model | Obs | ll(null) | ll(model) | df | AIC | BIC |
m_ANOVA | 3,465 | -9338.748 | -8050.892 | 721 | 17543.78 | 21978.27 |
m_mixed | 3,465 | . | -8316.189 | 37 | 16706.38 | 16933.94 |
Can you advise me about the most appropriate tests to conduct with my data?
Thank you very much.
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