This article might be too ambitious, I'm going to try it anyway. In 2013, Lifeway Research did a significant survey about small group Bible study. Their ultimate conclusion was that many small groups did not have the goal of making disciples of Jesus. They identified eight areas that seemed to be common to people maturing in their faith / growing in their relationship with Jesus. This was reported in the book Transformational Groups: Creating a New Scorecard for Groups.
Obeying God and Denying Self
Serving God and Others
Let me talk about these from a local church level. It's a pretty big, pretty amorphous list. Here's how we would use it: Ideally, the people in your Sunday School class or small group Bible study are demonstrating these traits, and they have opportunity to grow in them as a direct result of your group meetings. Let's look at these one at a time.
A growing disciple reads and studies and uses the Bible regularly. Life decisions are affected by what the Bible teaches. Your group should engage the Bible. But just as importantly, your group should be equipping group members to read and apply the Bible on their own.
Obeying God and Denying Self
A growing disciple echoes what John the Baptist said about Jesus: "He must increase, I must decrease." It's hard to "do" this (and many of the others) in a class meeting; this is about learning how to do it in life. But at the least, your group should be challenging members to change their tendencies and behaviors.
Serving God and Others
A growing disciple becomes more and more outward-focused. Life (and church) becomes less what "I" want and more what connects and engages others. At the least, your group should be identifying and organizing opportunities to take care of others. At best, your group should also be helping members look for such opportunities on their own.
A growing disciple tells others about Jesus. In my lessons, I like to try to include a gospel presentation every week (1) because there could be a non-Christian present, and (2) to make the language of the gospel more familiar to group members. Your group should be challenging members to share their faith and also helping them learn how to do it.
A growing disciple does what Jesus does: "Not my will but Yours, God". We trust what God is doing and seek to understand it. Your group should be built on a foundation of faith in God, which should make it a safe place for people to express their doubts and concerns. Our faith is not blind; God can handle our questions.
A growing disciple more and more seeks the kingdom before anything of this world. This includes wealth, power, prestige, etc. Your group should discuss practical ways every Bible passage encourages us to seek God and challenge members to do it.
A growing disciple needs mentors, peers, and people to teach. We need community, support, prayers, and guidance. Your group should emphasize relationships and give members opportunities to build them with each other as well as people who need to one day become a part of the group. That can't just happen on Sunday mornings.
A growing disciple is becoming more and more secure in their identity in Christ. They acknowledge their failures and learn from them. When shared in a small group, they help others learn from those failures. This works best when a group is trustworthy and discrete. Your group should be a safe place for Christians to share their struggles.
That's a pretty good picture of a disciple. All of those traits are important. You can't really emphasize all of them every week (you only have so much time). But you should have a plan to emphasize at least one of them every week, cycling through all of them over every quarter, say. That's doable. But it requires group leaders to be intentional.
The book, Transformational Groups, included several tables of survey results. I find them compelling. Here are some of the results. If anyone ever asks you if small groups help people become disciples of Jesus, here are your answers:
I think that table is good evidence for the value of small groups! And it also proves that our small groups are not always focused on the right things. (For example: "I regularly pray in a group with other Christians" is only 36% for people who attend a group regularly. What are they doing in that group??) So there you go. May these survey results be an encouragement and a challenge to you and your small group!
Let me point out one last thing with respect to using statistics and discipleship. It's important to understand this: you aren't trying to measure "discipleship" in absolute numbers. Or at least you shouldn't be. "Prayer" cannot be measured. "I pray three times a day." Okay - about what? For how long? How much effort and concentration do you put into it? Etc. These things can't be measured. And I also don't think we need to measure it in that way. What we want to know is if our group members are growing in those traits. Does that make sense? For example: you might have a class member who reads the Bible 3 times a day and another who reads it twice a week. Obviously, one is better than the other, right? Well, no. What if I mentioned that the one reading twice a week didn't read the Bible at all as of two months ago? That's real, significant growth, and it's important and meaningful! When it comes to discipleship, there aren't "benchmarks" or standardized tests. Our standard is Jesus, and our measure is who we were yesterday, the day before.
You can put these traits in front of your group members and ask them simple questions: how is your Bible engagement compared to where it was last year? How is it compared with where you think Jesus wants you to be? What is your plan for moving toward that level?