How to find Confidence of association rule in Apriori algorithm
<p>I am using Apriori algorithm to identify the frequent item sets of the customer.Based on the identified frequent item sets I want to prompt suggest items to customer when customer adds a new item to his shopping list.Assume my one identified frequent set is [2,3,5].My question is;</p>

<p>if user has already added item 2 and item 5, i want check the confidence of the rule to suggest item 3. for that; </p>

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<p>confidence = support of (2,3,5)/ support (3) ?</p>

<h2><strong>OR</strong></h2>

<p>confidence = support of (2,3,5)/ support (2,5)?</p>

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<p>which equation is correct? please help!!</p>