Statistics

Figure 1. Statistics table with bootstrap confidence interval for proportion
Table for Churn within last month with Customer category in the rows and bootstrap statistics in the columns

The statistics table shows, for each level of Customer category, the mean value for Churn within last month. Since Churn within last month only takes values 0 and 1, with 1 signifying a customer who churned, the mean is equal to the proportion of churners. The Statistic column shows the values usually produced by Frequencies, using the original dataset. The Bootstrap columns are produced by the bootstrapping algorithms.

  • Bias is the difference between the average value of this statistic across the bootstrap samples and the value in the Statistic column. In this case, the mean value of Churn within last month is computed for all 1000 bootstrap samples, and the average of these means is then computed.
  • Std. Error is the standard error of the mean value of Churn within last month across the 1000 bootstrap samples.
  • The lower bound of the 95% bootstrap confidence interval is an interpolation of the 25th and 26th mean values of Churn within last month, if the 1000 bootstrap samples are sorted in ascending order. The upper bound is an interpolation of the 975th and 976th mean values.

The results in the table suggest that the rate of churn differs across customer types. In particular, the confidence interval for Plus service customers does not overlap with any other, suggesting these customers are, on average, less likely to leave.

When working with categorical variables with only two values, these confidence intervals are alternatives to those produced by the One-Sample Nonparametric Tests procedure or the One-Sample T Test procedure.

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