▁Mar athon ▁male ▁w inners <0x0A> </s> ▁Statist ical ▁conclusion ▁valid ity ▁is ▁the ▁degree ▁to ▁which ▁conclus ions ▁about ▁the ▁relationship ▁among ▁variables ▁based ▁on ▁the ▁data ▁are ▁correct ▁or ▁" reason able ". ▁This ▁began ▁as ▁being ▁sole ly ▁about ▁whether ▁the ▁statistical ▁conclusion ▁about ▁the ▁relationship ▁of ▁the ▁variables ▁was ▁correct , ▁but ▁now ▁there ▁is ▁a ▁movement ▁towards ▁moving ▁to ▁" reason able " ▁conclus ions ▁that ▁use : ▁quant itative , ▁statistical , ▁and ▁qual itative ▁data . ▁Fund ament ally , ▁two ▁types ▁of ▁errors ▁can ▁occur : ▁type ▁I ▁( find ing ▁a ▁difference ▁or ▁correlation ▁when ▁none ▁exists ) ▁and ▁type ▁II ▁ ▁( find ing ▁no ▁difference ▁or ▁correlation ▁when ▁one ▁exists ). ▁Statist ical ▁conclusion ▁valid ity ▁concerns ▁the ▁qual ities ▁of ▁the ▁study ▁that ▁make ▁these ▁types ▁of ▁errors ▁more ▁likely . ▁Statist ical ▁conclusion ▁valid ity ▁involves ▁ens uring ▁the ▁use ▁of ▁ade qu ate ▁sampling ▁procedures , ▁appropriate ▁statistical ▁tests , ▁and ▁reliable ▁measurement ▁procedures . ▁ ▁Common ▁thre ats ▁The ▁most ▁common ▁thre ats ▁to ▁statistical ▁conclusion ▁valid ity ▁are : ▁ ▁Low ▁statistical ▁power ▁Power ▁is ▁the ▁probability ▁of ▁correctly ▁reject ing ▁the ▁null ▁hypothesis ▁when ▁it ▁is ▁false ▁( in verse ▁of ▁the ▁type ▁II ▁error ▁rate ). ▁Exper iments ▁with ▁low ▁power ▁have ▁a ▁higher ▁probability ▁of ▁incorrectly ▁accepting ▁the ▁null ▁hypothesis — that ▁is , ▁comm itting ▁a ▁type ▁II ▁error ▁and ▁con cluding ▁that ▁there ▁is ▁no ▁effect ▁when ▁there ▁actually ▁is ▁( I