Table 2

Logistic regression analysis of factors associated with attrition (player loss) after the debut round of play among University of Alabama at Birmingham (UAB) and University of Alabama at Huntsville (UAH) residents (n=117) participating in Kaizen-Internal Medicine during the 2012–2013 academic year

Number of playersPlayed next round
N (%) or
median (IQR)
Did not play next round
N (%) or
median (IQR)
Univariate*Multivariable†
Player class
 PGY14837 (77%)11 (23%)1.01.0
 PGY24327 (63%)16 (37%)1.99 (0.80 to 4.97)1.54 (0.49 to 4.79)
 PGY32614 (54%)12 (46%)2.88 (1.04 to 8.02)2.17 (0.59 to 7.94)
Debut round
 UAB round 19265 (71%)27 (29%)1.01.0
 UAB round 2‡101 (10%)9 (90%)21.65 (2.62 to 179.25)12.69 (1.34 to 120.15)
 UAH round 2‡1512 (80%)3 (20%)0.60 (0.16 to 2.30)1.33 (0.29 to 6.15)
Predominant play style§
 Daily4637 (80%)9 (20%)1.01.0
 Other7141 (58%)30 (42%)3.01 (1.26 to 7.16)2.82 (0.86 to 9.28)
Per cent correct**11768.5 (58.9 to 78.1)76.2 (66.7 to 86.0)1.39 (1.04 to 1.86)1.31 (0.84 to 2.05)
Per cent completed**11798.6 (66.4 to 100.0)42.1 (10.3 to 75.7)0.74 (0.65 to 0.84)0.81 (0.69 to 0.95)
  • *Results in the ‘univariate’ column are based on five separate logistic regression models each modelling attrition (Y/N) in the round after debut. p Values for the overall type 3 tests for the three-level categorical variables player class and debut round were 0.11 and 0.08, respectively.

  • †Results in the ‘multivariable’ column are based on a single logistic regression model modelling attrition (Y/N) in the round after debut. The model included player class, debut round, predominant play style, per cent correct and per cent completed. p Values for the overall type 3 tests for the three-level categorical variables player class and debut round were 0.49 and 0.08, respectively.

  • ‡ UAB round 2 debut players include individuals who did not play in round 1, but joined in round 2. UAH players were invited to participate for rounds 2 and 3, but did not play in round 1.

  • §Predominant play style was defined as the play style used by each participant the majority of the time. Daily players most often completed their questions on the day of release; catch-up (2–6 days of questions at a time) and binge (>7 days of questions at a time) are collapsed into the 'other' category.

  • **Per cent correct and per cent completed included in models as continuous variables. ORs represent per 10% increase.

  • PGY, postgraduate year.