Recommendations vary considerably for the minimum or optimal number of baseline sessions to conduct within single-case experimental design clinical analyses or research studies. We examined the optimal number of baseline sessions that produced minimal bias. First, we examined the relation between the number of baseline sessions and the degree of bias in calculating estimates of treatment effect size. As the number of baseline sessions increased, the bias in effect size estimates decreased, r = -0.36, p < 0.001. s, we examined what would be the minimum number of baseline sessions associated with varying levels of bias. Bias of approximately ten percent was associated with four to five baseline sessions. Bias of about five percent was associated with six to seven baseline sessions. Third, we examined the relation between standard deviation and varying levels of bias. As the number of baseline sessions increases, the standard deviation for the phase decreased, r = -0.89, p < 0.001. Fourth, we examined what value of standard deviation in the baseline phase was associated with equal to or more than five versus ten percent bias. When considering five or ten percent bias, the optimal level of standard deviation was 0.59 or less.

对于在单案例实验设计临床分析或研究中进行的最小或最佳基线会话数，建议差异很大。我们检查了产生最小偏差的最佳基线会话数。首先，我们在计算治疗效果大小的估计值时检查了基线会话次数与偏差程度之间的关系。随着基线会话次数的增加，效应量估计的偏差减小，r = -0.36，p< 0.001。s，我们检查了与不同程度的偏见相关的最小基线会话数是多少。大约 10% 的偏差与四到五个基线会话相关。大约 5% 的偏差与 6 到 7 个基线会话相关。第三，我们检查了标准偏差和不同程度的偏差之间的关系。随着基线会话次数的增加，阶段的标准偏差降低，r = -0.89，p < 0.001。第四，我们检查了基线阶段的标准偏差值与等于或大于 5% 和 10% 的偏差相关联。在考虑 5% 或 10% 的偏差时，标准偏差的最佳水平为 0.59 或更低。