据此认为，跑后动脉血氧分压分别与年龄、跑完1000米用时呈负相关关系，与体重和跑时平均脉搏数无关。（6分）
问：（1）该资料有什么特点?
（2）采用的统计方法是否正确?
（3）该资料应该用何种统计方法？
9. 某医师对25名健康男性教工测定年龄（age）、体重(weight)、跑完1000米用时(time)、跑时平均脉搏数(pulse)、跑后动脉血氧分压(bloodo),测定结果后以跑后动脉血氧分压(bloodo)作应变量，年龄（age）、体重(weight)、跑完1000米用时(time)、跑时平均脉搏数(pulse)为自变量，进行逐步回归分析结果如下，请给予解释。（7分）
Model 1 2 3
R .673(a) .827(b) .864(c)
Adjusted R Std. Error of
R Square Square the Estimate
.453 .684 .747
.429 .656 .711
.63859 .49571 .45406
ModelSummary
a Predictors: (Constant), AGE，b Predictors: (Constant), AGE, TIME，c Predictors: (Constant), AGE, TIME, PULSE ANOVA(d) Model
1 Regression
<>
9.379 23
Residual
<>
17.133 24
2
Total
Regression <>
5.406 22
Residual <>
17.133 24
3
Total
Regression <>
4.330 21
Residual <>
17.133 24
Total
a Predictors: (Constant), AGE
.206
.246
.408
Sum of Squares
df Mean Square
F
Sig. .000(a)
7.754 1 7.754 19.014
11.727 2 5.863 23.862 .000(b)
12.803 3 4.268 20.700 .000(c)
b Predictors: (Constant), AGE, TIME
c Predictors: (Constant), AGE, TIME, PULSE
d Dependent Variable: BLOODO
Coefficients(a)
Model Unstandardized Standardized Coefficients Coefficients B Std. Error Beta 1 (Constant) 11.101 1.105 AGE -.101 .023 -.673
2 (Constant) 13.061 .986 AGE -.089 .018 -.598 TIME -.448 .112 -.487 3 (Constant) 8.810 2.068 AGE -.