clean up extrpaolation procedure explanations

Author: shellmayr

develop-docs/application-architecture/dynamic-sampling/extrapolation.mdx

@@ -35,17 +35,16 @@ Sentry allows the user to aggregate data in different ways - the following aggre
 Each of these aggregates has their own way of dealing with extrapolation, due to the fact that e.g. counts have to be extrapolated in a slightly different way from percentiles. 
 
 ### Extrapolation for different aggregates
-To extrapolate, the sampling weights have to be used in the following ways:
+To extrapolate, sampling weights are calculated as 1/(sample rate). The sampling weights then are used in the following ways:
 
 - **Count**: Calculate a sum of the sampling weight
 Example: the query `count()` becomes `round(sum(sampling weight))`.
 - **Sum**: Multiply each value with `sampling weight`.
 Example: the query `sum(foo)` becomes `sum(foo * sampling weight)`
-- **Average**: Use avgWeighted with sampling weight.
+- **Average**: Calculate the weighted average with sampling weight.
 Example: the query `avg(foo)` becomes `avgWeighted(foo, sampling weight)`
-- **Percentiles**: Use `*TDigestWeighted` with `sampling_weight_2`.
-We use the integer weight column since weighted functions in Clickhouse do not support floating point weights. Furthermore, performance and accuracy tests have shown that the t-digest function provides best runtime performance (see Resources below). 
-Example: the query `quantile(0.95)(foo)` becomes `quantileTDigestWeighted(0.95)(foo, sampling_weight_2)`.
+- **Percentiles**: Calculate the weighted percentiles with sampling weight.
+Example: the query `quantile(0.95)(foo)` becomes `weightedPercentile(0.95)(foo, sampling weight)`.
 
 As long as there are sufficient samples, the sample rate itself does not matter as much, but due to the extrapolation mechanism, what would be a fluctuation of a few samples, may turn into a much larger absolute impact e.g. in terms of the view count. Of course, when a site gets billions of visits, a fluctation of 100.000 via the noise introduced by a sample rate of 0.00001 is not as critical.