Table 3.
OLS regression of standardized knot rating scores on the generation and treatment (one-model/five-model), and their interaction, controlling for male, age (standardized) and knot-tying experience. By alternating the dummy coding of treatment, this table directly compares the effect of generation by looking at the generation coefficients. The loss of skill within both the first three generations and the last seven generations is twice as fast in the one-model treatment compared to the five-model treatment. We conducted a test of joint significance of treatment and treatment–generation interaction by statistically comparing regression models with and without these variables—see electronic supplementary material, table S6. The results indicate a statistically significant effect of treatment and treatment–generation interaction.
| one model: 1–3 | five models: 1–3 | one model: 4–10 | five models: 4–10 | |
|---|---|---|---|---|
| generation | −0.67 (0.28)* | −0.25 (0.28) | −0.07 (0.05) | −0.03 (0.05) |
| five-model | 0.28 (0.85)** | 0.78 (0.52)** | ||
| five-model generation* | 0.42 (0.38)** | 0.03 (0.07)** | ||
| one-model | −0.28 (0.85)** | −0.78 (0.52) | ||
| one-model generation* | −0.42 (0.38)** | −0.03 (0.07) | ||
| age | 0.07 (0.14) | 0.07 (0.14) | −0.02 (0.09) | −0.02 (0.09) |
| male | 0.41 (0.37) | 0.41 (0.37) | 0.34 (0.18) | 0.34 (0.18) |
| sailing knot experience | 0.11 (0.21) | 0.11 (0.21) | 0.01 (0.08) | 0.01 (0.08) |
| climbing knot experience | 0.19 (0.33) | 0.19 (0.33) | 0.07 (0.07) | 0.07 (0.07) |
| (intercept) | 1.40 (0.63)* | 1.68 (0.65)** | −0.44 (0.38) | 0.34 (0.38) |
| R2 | 0.518 | 0.518 | 0.524 | 0.524 |
| adj. R2 | 0.365 | 0.365 | 0.471 | 0.471 |
| n | 30 | 30 | 70 | 70 |
*p < 0.05; **p < 0.01.