simstudy：genData 产生相同的值

Question

这是我第一次尝试模拟数据 - 我们想模拟一个数据集，并选择使用以下代码使用 simstudy：

def <- defData(varname='median_household_income',formula=mean(
               df$median_household_income))
def <- defData(def, varname='share_unemployed_seasonal',formula=mean(
               df$share_unemployed_seasonal))
def <- defData(def, varname='share_population_in_metro_areas',
               formula=mean(df$share_population_in_metro_areas))
def <- defData(def, varname='share_population_with_high_school_degree',
               formula=mean(df$share_population_with_high_school_degree))
def <- defData(def, varname='share_non_citizen',
               formula=mean(df$share_non_citizen))
def <- defData(def, varname='share_white_poverty',
               formula=mean(df$share_white_poverty))
def <- defData(def, varname='gini_index',formula=mean(df$gini_index))
def <- defData(def, varname='share_non_white',formula=mean(df$share_non_white))
def <- defData(def, varname='share_voters_voted_trump',
               formula=mean(df$share_voters_voted_trump))
#outcome
def <- defData(def, varname='avg_hatecrimes_per_100k_fbi',formula=
               ".0001*median_household_income + 44*share_unemployed_seasonal + 
               -2.8*share_population_in_metro_areas +
               24*share_population_with_high_school_degree + 22*share_non_citizen + 
               3.2*share_white_poverty + 55*gini_index + -4*share_non_white + 
               -2.6*share_voters_voted_trump")

#generate simulated data
df_sim <- genData(10000,def)

输出如下所示：

 head(df_sim)
 id median_household_income share_unemployed_seasonal share_population_in_metro_areas
1:  1                55223.61                0.04956863                       0.7501961
2:  2                55223.61                0.04956863                       0.7501961
3:  3                55223.61                0.04956863                       0.7501961
4:  4                55223.61                0.04956863                       0.7501961
5:  5                55223.61                0.04956863                       0.7501961
6:  6                55223.61                0.04956863                       0.7501961

为什么生成的值都是一样的？我的理解是默认情况下变量是根据正态分布生成的。对此的任何帮助表示赞赏！

Answer 1

我发现您指的是一个包 simstudy。如果您查看 defData 函数 (link here) 的文档，您会发现 defData 函数的 variance 参数默认为零。如果你想有不同的观察结果，你需要将这个值设置为大于 0 的数字。

defData 函数的默认行为：

defData(dtDefs = NULL, varname, formula, variance = 0,
  dist = "normal", link = "identity", id = "id")

所以你可能想要运行像

这样的命令

def <- defData(varname='median_household_income',
               formula=mean(df$median_household_income),
               variance = 1)

simstudy：genData 产生相同的值

simstudy: genData producing identical values

simulation

r

package