When using the FP-Growth algorithm for association analysis, the support threshold is a crucial parameter that needs to be set before mining the frequent itemsets. The support threshold determines the minimum frequency of itemsets that will be considered frequent and used in generating association rules.
Here are some steps that can help in deciding the reasonable support in association analysis using FP-Growth algorithm:
Understand the dataset: Before deciding on the support threshold, it's important to understand the characteristics of the dataset. The size of the dataset, the number of unique items, and the distribution of itemsets can influence the choice of support threshold.
Determine the objective: The objective of the analysis will also influence the choice of support threshold. If the goal is to identify all the frequent itemsets, then a low support threshold may be appropriate. On the other hand, if the objective is to identify strong association rules, then a higher support threshold may be needed to reduce the number of itemsets.
Use domain knowledge: Domain knowledge can be used to set a reasonable support threshold. For example, if the dataset contains items that are known to be frequently purchased together, then a higher support threshold may be appropriate.
Experiment with different support thresholds: It's a good practice to experiment with different support thresholds to identify the threshold that generates the most relevant frequent itemsets. The support threshold can be gradually increased or decreased until a reasonable set of frequent itemsets is obtained.
Evaluate the results: Finally, it's important to evaluate the results of the association analysis to ensure that the generated frequent itemsets and association rules are meaningful and useful. If the results are not satisfactory, then the support threshold can be adjusted and the analysis can be repeated.
In summary, determining the reasonable support threshold in association analysis using the FP-Growth algorithm requires a good understanding of the dataset, the objective of the analysis, domain knowledge, experimentation, and evaluation of the results.