Because　of　the　vast　volume　of　data　being　produced　by　today＇s　scientific　simulations　and　experiments,　lossy　data　compressor　allowing　user-controlled　loss　of　accuracy　during　the　compression　is　a　relevant　solution　for　significantly　reducing　the　data　size.　However,　lossy　compressor　developers　and　users　are　missing　a　tool　to　explore　the　features　of　scientific　data　sets　and　understand　the　data　alteration　after　compression　in　a　systematic　and　reliable　way.　To　address　this　gap,　we　have　designed　and　implemented　a　generic　framework　called　Z-checker.　On　the　one　hand,　Z-checker　combines　a　battery　of　data　analysis　components　for　data　compression.　On　the　other　hand,　Z-checker　is　implemented　as　an　open-source　community　tool　to　which　users　and　developers　can　contribute　and　add　new　analysis　components　based　on　their　additional　analysis　demands.　In　this　article,　we　present　a　survey　of　existing　lossy　compressors.　Then,　we　describe　the　design　framework　of　Z-checker,　in　which　we　integrated　evaluation　metrics　proposed　in　prior　work　as　well　as　other　analysis　tools.　Specifically,　for　lossy　compressor　developers,　Z-checker　can　be　used　to　characterize　critical　properties　(such　as　entropy,　distribution,　power　spectrum,　principal　component　analysis,　and　autocorrelation)　of　any　data　set　to　improve　compression　strategies.　For　lossy　compression　users,　Z-checker　can　detect　the　compression　quality　(compression　ratio　and　bit　rate)　and　provide　various　global　distortion　analysis　comparing　the　original　data　with　the　decompressed　data　(peak　signal-to-noise　ratio,　normalized　mean　squared　error,　rate-distortion,　rate-compression　error,　spectral,　distribution,　and　derivatives)　and　statistical　analysis　of　the　compression　error　(maximum,　minimum,　and　average　error;　autocorrelation;　and　distribution　of　errors).　Z-checker　can　perform　the　analysis　with　either　coarse　granularity　(throughout　the　whole　data　set)　or　fine　granularity　(by　user-defined　blocks),　such　that　the　users　and　developers　can　select　the　best　fit,　adaptive　compressors　for　different　parts　of　the　data　set.　Z-checker　features　a　visualization　interface　displaying　all　analysis　results　in　addition　to　some　basic　views　of　the　data　sets　such　as　time　series.　To　the　best　of　our　knowledge,　Z-checker　is　the　first　tool　designed　to　assess　lossy　compression　comprehensively　for　scientific　data　sets.