In general, six elements appear  purpose, type of data collected, method of data collection, design, method of data analysis, and reporting.
( ( In general ) ( , ( ( six elements ) ( ( appear ( ( purpose , ) ( type ( of ( ( ( ( ( ( ( ( ( ( data collected ) , ) ( method ( of ( data collection ) ) ) ) , ) design ) , ) ( method ( of ( data analysis ) ) ) ) , ) and ) reporting ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NN general))) (, ,) (NP (CD six) (NNS elements)) (VP (VBP appear) (NP (NP (NN purpose)) (, ,) (NP (NP (NN type)) (PP (IN of) (NP (NP (NP (NNS data)) (VP (VBN collected))) (, ,) (NP (NP (NN method)) (PP (IN of) (NP (NN data) (NN collection)))) (, ,) (NP (NN design)) (, ,) (NP (NP (NN method)) (PP (IN of) (NP (NN data) (NN analysis)))) (, ,) (CC and) (NP (NN reporting))))))) (. .)))
Purpose is one of the six elements that appeared.
( Purpose ( ( is ( ( one ( of ( the ( six elements ) ) ) ) ( that appeared ) ) ) . ) )
(ROOT (S (NP (NNP Purpose)) (VP (VBZ is) (NP (NP (CD one)) (PP (IN of) (NP (DT the) (CD six) (NNS elements))) (SBAR (WHNP (WDT that)) (S (VP (VBD appeared)))))) (. .)))