MetricValue

A metric value, with an expected value and a variance; represents a count that may be either exact or estimated (for example, when sampled).

JSON representation 
{
  "value": string,
  "variance": string
}
Fields
value

string (int64 format)

The expected value of the metric.
variance

string (int64 format)

The variance (for example, square of the standard deviation) of the metric value. If value is exact, variance is 0. Can be used to calculate margin of error as a percentage of value, using the following formula, where Z is the standard constant that depends on the preferred size of the confidence interval (for example, for 90% confidence interval, use Z = 1.645):

marginOfError = 100 * Z * sqrt(variance) / value