1-tailed t-test for seeing if measures of arm length spanning a hexamer, that is from the outer edges of one CRD through the N terminal junctions and out another arm to the other CRD. of a diameter (touching 3 of the four CRD trimers at the ends of at least 3 of the four arms of SP-D (the smallest diameter able to be made).

Previous t-test has not shown a difference, however using all measures to date which includes AFM, rotary shadowed and negative stained images (all available in published documents) there may be a significant difference between methods. Below n=291 arms (which is 145 dodecamers) using the two methods (where n=diameter is
half as many as the separate measures of two hexameric arms.
Difference Scores Calculations

Two hexamers measured with a vector/node line running from CRD to CRD)
N1: 291
df1 = N – 1 = 291 – 1 = 290
M1: 133.8
SS1: 187767.45
s21 = SS1/(N – 1) = 187767.45/(291-1) = 647.47
One measurement of the smallest diameter which touches the outer edge of three of the four CRD.
N2: 146
df2 = N – 1 = 146 – 1 = 145
M2: 127.48
SS2: 82472.16
s22 = SS2/(N – 1) = 82472.16/(146-1) = 568.77
T-value Calculation one-tailed
s2p = ((df1/(df1 + df2)) * s21) + ((df2/(df2 + df2)) * s22) = ((290/435) * 647.47) + ((145/435) * 568.77) = 621.24
s2M1 = s2p/N1 = 621.24/291 = 2.13
s2M2 = s2p/N2 = 621.24/146 = 4.26
t = (M1 – M2)/√(s2M1 + s2M2) = 6.32/√6.39 = 2.5
The 1-tailed t-value is 2.49859. The p-value is .006418. The result is significant at p < .05. The 2-tailed t-value is 2.49859. The p-value is .012837. The result is significant at p < .05 Values from the two measurement approaches when the Arroyo mislabeled nm cover image measurements are removed from each type of measurement Difference Scores Calculations Two hexamers measured with a vector/node line running from CRD to CRD) N1: 261 df1 = N - 1 = 261 - 1 = 260 M1: 128.16 SS1: 104135.99 s21 = SS1/(N - 1) = 104135.99/(261-1) = 400.52 One measurement of the smallest diameter which touches the outer edge of three of the four CRD. N2: 131 df2 = N - 1 = 131 - 1 = 130 M2: 122.42 SS2: 47925.59 s22 = SS2/(N - 1) = 47925.59/(131-1) = 368.66 T-value Calculation s2p = ((df1/(df1 + df2)) * s21) + ((df2/(df2 + df2)) * s22) = ((260/390) * 400.52) + ((130/390) * 368.66) = 389.9 s2M1 = s2p/N1 = 389.9/261 = 1.49 s2M2 = s2p/N2 = 389.9/131 = 2.98 t = (M1 - M2)/√(s2M1 + s2M2) = 5.74/√4.47 = 2.71 The 2-tailed t-value is 2.71485. The p-value is .006925. The result is significant at p < .05