ArmLengthConversion.xlsx

Conversion for Pisaster ochraceus Arm Length Measurements To enable P. ochraceus size comparisons between California and Oregon and to allow other researchers to easily convert between arm lengths using different published methods, we measured arm lengths of 25 sea stars ranging in arm length from ~5-200mm at each of 6 sites in Oregon (see manuscript) using both measurement approaches. To determine whether site influenced this conversion, we first ran a linear model with madreporite measure as the response variable and site and center measure as the interacting factors. No interacting effect of site and arm measurement from center to arm tip was found (F5,138 = 0.64, P = 0.672), suggesting this metric is consistent geographically, at least within Oregon. We had no data for California. So, we used a simple linear regression (R2 = 0.97, P < 0.001) to convert madreporite measures to center measures for all our data. Conversion formulas in centimeters are: [madreporite arm length = 4.074 + (1.060*center arm length)] or [center arm length= -0.729 + (0.914*madreporite arm length)].

紫海盘车（Pisaster ochraceus）腕长测量转换方法
为实现加州与俄勒冈州两地紫海盘车的体型对比，并便于其他研究人员基于不同已发表方法实现腕长数据的便捷转换，本研究针对俄勒冈州6个采样点（详见论文手稿）的各25只腕长范围约5~200mm的海盘车，采用两种测量方案开展腕长测定。
为探究采样点是否对该转换存在影响，本研究首先构建线性模型，以筛板（madreporite）测量值作为响应变量，以采样点与中央腕长测量值作为交互因子。分析未发现采样点与腕尖至中央的腕长测量值之间存在交互效应（F₅,₁₃₈=0.64，P=0.672），表明该测量指标在地理上具有一致性，至少在俄勒冈州范围内如此。
本研究未获取加州地区的相关数据，因此针对全部数据集，我们采用简单线性回归（决定系数R²=0.97，P<0.001）实现筛板测量值与中央腕长测量值之间的转换。以厘米为单位的转换公式如下：
[筛板腕长 = 4.074 + (1.060 × 中央腕长)] 或 [中央腕长 = -0.729 + (0.914 × 筛板腕长)]。