Adding expectation functions

[edward-burn]

A bit like https://rstudio.github.io/pointblank/index.html, we can have some expectation functions to help assess the diagnostics results. The user gives some expectations and we check if these are met in the result

Some simple ones to start with:

• is median age in a given range
• is proportion male (vs female) in a given range

Need @albertpratsu to help think about how best to incorporate

[edward-burn]

expectations dataset

• expectation_name
• expectation_description

summarised result columns ..... (so that we know which result this would refer too)

• group_level, group_name, etc ..... ?

thresholds

• threshold_lower
• threshold_upper

[edward-burn]

probably would be difficult for the user to know all the summarised resut columns etc, so probably easier to start with prespecified like median age etc (which we can find easily enough in the code)