MA Star Ratings by parent, product type or state, year over year. For a rating year against the year before: members in rated and unrated contracts, the member-weighted Overall star, the share of members (and of contracts) at 4 stars or more, and members by Overall star. Optionally the weighted measure star for a measure group, like for like.

ARGUMENTS: rating_year (default the newest with Overall stars), compare_year (default rating_year minus 1), group_by (national | parent | product_type | parent_by_product | state | state_by_product), parent (filter: part of the parent organization's name, e.g. 'UnitedHealth'), product_type (filter: nonsnp_hmo | nonsnp_ppo | dsnp_hmo | dsnp_ppo | csnp_hmo | csnp_ppo | isnp | other), state (filter: two-letter code), measure_group (optional: all | part_c | part_d | patient_safety | domain:<CMS domain code, e.g. HD3 or DD4> | source:<CMS data source, e.g. HEDIS, CAHPS, HOS, PDE> | measure:<measure identity key, e.g. c:controlling_blood_pressure>), limit (default 50, largest rated members first).

RETURNS value.rows (one per group), each with members_rated, members_unrated, contracts_rated, contracts_unrated, pct_members_4plus, wtd_avg_star, pct_contracts_4plus, members_by_star, prior (the same fields for compare_year) and change; with measure_group, a measure_group block {measures, contracts, wtd_measure_star, wtd_measure_star_prior, change}. value.summary is the national row for the same filters, with each year's weight month.

RULES THE TOOL ENFORCES: rating year Y is weighted by December of the payment year (Y+1), or the latest month when that December is not published, and says which (the certified house convention); the parent is the enrollment file's parent at the weight month; stand-alone drug plans are out; unrated contracts are counted apart, never as zero stars; product types are the fixed buckets (non-SNP, D-SNP, C-SNP by HMO and PPO; I-SNP; other), never pooled; a star belongs to the contract, so a product type or state row weights the contract's star by its members there; a measure group change compares the same contracts, measures, weights (the rating year's) and members, and leaves out new measures, re-specified measures and the improvement measures. Measure stars are CMS's normalization; raw scores are never averaged across measures.

SOURCE: CMS Part C and D Star Ratings Data Tables and CMS monthly enrollment (contract, plan, SNP and county files).