Do Accountability Partners Work? Two Studies, Run Through the Numbers
Updated: 1 day ago
"Tell someone your goal" is the advice everyone gives and almost nobody quantifies. Two studies did measure it, with different goals, different people, and different follow-up periods. We took the figures each one published and worked out how much of the total effect comes from the friend.
Study one: five groups, one month, 149 people
Psychologist Gail Matthews at Dominican University of California ran a goal-achievement experiment and published a research summary with the full design and results. She recruited 267 working adults, aged 23 to 72, from businesses and networking groups in six countries. They were randomly assigned to one of five groups and given four weeks to pursue a goal of their choosing, such as finishing a project, increasing income, or getting organized. 149 completed the study, a 56 percent completion rate, which is worth keeping in mind.
The five groups were:
Think about the goal, but do not write it down.
Write the goal down.
Write the goal and a list of action commitments.
Write the goal and action commitments, and send them to a supportive friend.
Do all of the above, and send that friend a weekly progress report.
At the end of four weeks, everyone rated how far they had got. The mean achievement scores were 4.28, 6.08, 5.08, 6.41, and 7.60 for groups one through five. The summary reports that group five scored significantly higher than every other group, group four scored significantly higher than groups three and one, and group two scored significantly higher than group one.
What each step adds
Our method was to express each group's mean as a percentage of the group it builds on, then measure the two "friend" steps against the total spread between the lowest and highest groups. Ratios are rounded to the nearest percent.
Writing the goal down (group 2 versus group 1): 6.08 against 4.28, a 42 percent lift.
Adding a private action plan (group 3 versus group 2): 5.08 against 6.08, a 16 percent drop. The summary does not report this difference as significant, so the fair reading is that a plan nobody sees added nothing.
Sending the plan to a friend (group 4 versus group 3): 6.41 against 5.08, a 26 percent lift.
Adding weekly progress reports to that friend (group 5 versus group 4): 7.60 against 6.41, a 19 percent lift.
Everything versus nothing (group 5 versus group 1): 7.60 against 4.28, a 78 percent lift.
The spread from the worst group to the best is 3.32 points. The two friend steps, from private planner to weekly reporter, cover 2.52 of those points. That is 76 percent of the entire effect, and it comes from the same person doing the same planning with one difference: someone else can see it.
One more detail from the design. Group five was not left to remember on its own. The researchers sent weekly reminders to email the friend. The accountability came with a nudge attached.
Study two: ten months, 166 people, a hard outcome
Self-rated progress on a self-chosen goal is a soft measure. The second study used a scale. In 1999, Rena Wing and Robert Jeffery published a weight-loss trial in the Journal of Consulting and Clinical Psychology with 166 participants. Some were recruited alone and given a standard behavioral program. Others were recruited together with three friends or family members and given the same program plus a social-support component built around the group.
The two outcomes reported in the abstract:
Completed the program: 76 percent of those recruited alone, 95 percent of those recruited with friends. Dividing the two, the friend group was 25 percent more likely to finish.
Kept their full weight loss from month four to month ten: 24 percent of those recruited alone, 66 percent of those recruited with friends. The friend group was 2.75 times as likely to hold the result.
The effect on finishing was moderate. The effect on maintaining was large. Friends did not just get people through the program; they kept the behavior going for six months after the structured part ended, which is the stretch where most habits die.
The caveats, honestly
Neither study is perfect, and the numbers are more useful if you know their limits.
The Matthews study lost 44 percent of its starters before the end, the outcome was self-reported, and the groups were small. The Wing and Jeffery study bundled "recruited with friends" together with an extra social-support program, so the abstract's comparison is not a clean test of the friend alone. Both are consistent with each other, and with decades of social-psychology findings on public commitment, but they are two studies, not a law.
What they agree on is specific. Writing a goal helps a little. Planning in private helps less than people assume. Letting one person see your progress, repeatedly, is where the bulk of the gain sits.
From weekly to daily
In the Matthews study, the winning group reported once a week. A daily habit gives you seven chances a week to be seen, and the report can be far shorter than an email.
That is the design of Habit Textapp. Each day you get one text asking whether you did your habit. You reply yes or no. Ask for an invite code, and when a friend texts the number with it, you each see whether the other checked in that day. The friend does not need the same habit, the same phone, or any app. The weekly reminder that Matthews' group five needed is built in, and it arrives every day.
A few things help when choosing the buddy:
Pick someone who will notice a skip, not someone who will scold one. The study measured being seen, not being punished.
One buddy is enough. The Wing trial used groups of four, but the mechanism was that someone expected you to show up.
Agree on the habit before the first check-in so the buddy knows what "done" means.
Try it by text
Habit Textapp is a daily check-in for one habit with a buddy who sees whether you did it. Text Hi to (332) 301-4574, tell it the habit you want to build, and each day it asks one question. Reply yes or no, ask how you are doing to see your last seven days, and ask for an invite code for your friend.
It works on any phone that can text, with no app to install and no account to create. Your first 20 messages are free. Details are at textapp.co/apps/habit.
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