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12.1.7 Crosshead speed （rate of grip separation）,
12.1.8 Gage length （if different from grip separation）,
12.1.9 Type of grips used, including facing （if any）,
12.1.10 Conditioning procedure （test conditions, temperature,
and relative humidity if nonstandard）,
12.1.11 Anomalous behavior such as tear failure and failure
at a grip,
12.1.12 Average breaking factor and standard deviation,
12.1.13 Average tensile strength （nominal） and standard
deviation,
12.1.14 Average tensile strength at break （nominal） and
standard deviation,
12.1.15 Average percent elongation at break and standard
deviation,
12.1.16 Where applicable, average tensile energy to break
and standard deviation,
12.1.17 In the case of materials exhibiting “yield” phenomenon:
average yield strength and standard deviation; and
average percent elongation at yield and standard deviation,
12.1.18 For materials which do not exhibit a yield point:
average —% offset yield strength and standard deviation; and
average percent elongation at —% offset yield strength and
standard deviation,
12.1.19 Average modulus of elasticity and standard deviation
（if secant modulus is used, so indicate and report strain at
which calculated）, and
12.1.20 When an extensometer is employed, so indicate.
13. Precision and Bias
13.1 Two interlaboratory tests have been run for these
tensile properties. The first was run for modulus only, in 1977,
in which randomly drawn samples of four thin （; 0.025 mm
（0.001-in.）） materials were tested with five specimens in each
laboratory. Elastic （tangent） modulus measurements were
made by six laboratories, and secant （1 %） modulus measurements
were taken by five laboratories. The relative precision
obtained in this interlaboratory study is in Table 2.
13.1.1 In deriving the estimates in Table 2, statistical
outliers were not removed, in keeping with Practice E 691.9
13.1.2 The within-lab standard deviation of a mean value, S
x? , in each case was determined from the standard deviation, S
x? , of the five individual specimens as follows: S x? = Sx /（5）1?2.
The S x? values were pooled among laboratories for a given
material to obtain the within-lab standard deviation, Sr , of a
test result （mean of five specimens）. See 13.3-13.3.2 for
definitions of terms in the tables.
13.2 An interlaboratory test was run for all the other tensile
properties except modulus in 1981, in which randomly drawn
samples of six materials （one of these in three thicknesses）
ranging in thickness from 0.019 to 0.178 mm （0.00075 to 0.007
in.） were tested in seven laboratories. A test result was defined
as the mean of five specimen determinations. However, each
laboratory tested eight specimens, and the S x? was determined
from S x? = Sx /（5）1?2 as above. This was done to improve the
quality of the statistics while maintaining their applicability to
a five-specimen test result. The materials and their thicknesses
are identified in Tables 3-7, each of which contain data for one
of the following properties: tensile yield stress, yield elongation,
tensile strength, tensile elongation at break, and tensile
9 Supporting data are available from ASTM Headquarters. Request RR: D20-
1084.
TABLE 3 Precision Data for Yield Stress
Material Thickness, mils Average, 103 psi （Sr）A 103 psi （SR）B 103 psi I（r）C 103 psi I（R）D 103 psi
LDPE 1.0 1.49 0.051 0.13 0.14 0.37
HDPE 1.0 4.33 0.084 0.16 0.24 0.44
PP 0.75 6.40 0.13 0.52 0.37 1.46
PC 4.0 8.59 0.072 0.29 0.20 0.82
CTA 5.3 11.4 0.12 0.50 0.34 1.43
PET 4.0 14.3 0.12 0.23 0.34 0.66
PET 2.5 14.4 0.14 0.54 0.40 1.52
PET 7.0 14.4 0.13 0.36 0.37 1.03
A S r is the within-laboratory standard deviation of the average.
B SR is the between-laboratories standard deviation of the average.
C Ir = 2.83 Sr.
D I R = 2.83 SR.
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