The com pa ri son of met ho ds expe ri me nt is im por ta nt pa rt in pro ce ss of ana lyti cal met ho ds and in stru men ts va li da tion. Pas si ng and Bab lok reg ression ana lysis is a sta tis ti cal pro ce du re that al lows va luab le es ti ma tion of ana lyti cal met ho ds ag ree me nt and pos sib le syste ma tic bias be tween them. It is ro bu st, no n-pa ra met ric, non sen si ti ve to dis tri bu tion of errors and da ta out lie rs. As sum ptio ns for pro per ap pli ca tion of Pas si ng and Bab lok regres sion are con ti nuous ly dis tri bu ted da ta and li near re la tion ship be tween da ta mea su red by two ana lyti cal met ho ds. Re sul ts are pre sen ted wi th scat ter diag ram and reg res sion li ne, and reg res sion equa tion whe re in ter ce pt rep re sen ts con sta nt and slo pe pro por tio nal mea su re me nt er ror. Confi den ce in ter va ls of 95% of in ter ce pt and slo pe explain if their va lue diff er from va lue ze ro (in ter ce pt) and va lue one (slo pe) on ly by chan ce, al lowi ng con clu sion of met hod ag ree me nt and cor rec tion ac tion if ne ces sa ry. Re si dual plot re vea led out lie rs and iden ti fy pos sib le no n-li nea ri ty. Fur ther mo re, cu mu la ti ve sum li nea ri ty te st is per for med to in ves ti ga te pos sib le sig ni fi ca nt de via tion from li nea ri ty be tween two sets of da ta. Non li near sam ples are not sui tab le for con clu di ng on met hod ag ree me nt. Key wor ds: com pa ri son of met ho ds; data ana lysis; Pas si ng and Bab lok reg res sion Lessons in biostatistics In tro duc tionMet hod and in stru me nt va li da tion is im por ta nt issue in cli ni cal la bo ra to ry wo rk. Ea ch new met hod shou ld be va li da ted when in tro du ci ng in rou ti ne la bo ra to ry wo rk (1,2). Amo ng diff e re nt expe ri ments that shou ld be per for med to ac ce ss met ho d's per for man ce (pre ci sion and ac cu ra cy) the re is the com pa ri son of met ho ds expe ri me nt (3). That experi me nt com pa res re sul ts ob tai ned usi ng new method to tho se ob tai ned usi ng ot her ana lyti cal method. The ideal con di tion is ac hie ved if ana lyti cal met hod used for com pa ri son is re fe ren ce or de fini ti ve met hod. Cor rec tne ss of re fe ren ce met hods is no n-ques tio nab le, so new met hod re sul ts should be fi t ted ac cor di ng to the re fe ren ce. Howe ver, in usual cir cum stan ces in rou ti ne la bo ra to ry, cor rectne ss of met ho ds is not we ll do cu men ted so they can not be con si dered as re fe ren ce met hods; de fini ti ve met ho ds are una vai lab le, and re sul ts can be com pa red to "com pa ra ti ve met hod" -one avai lable and used in dai ly rou ti ne wo rk.The aim of the com pa ri son of met ho ds expe ri ment is to es ti ma te syste ma tic (con sta nt and pro portio nal) diff e ren ce be tween two met ho ds e.g. to find out if the re is sig ni fi ca nt diff e ren ce in their re lati ve ac cu ra cy usi ng real pa tie nt sam ples (3). Re sul ts shou ld be in ter pre ted ve ry ca re ful ly. If the diff eren ce be twee...

Aim To develop and test the psychometric characteristics of a questionnaire measuring attitudes toward plagiarism.Methods Participants were 227 undergraduates and graduate students (128 women and 99 men) from three Croatian universities, with a median age of 21 years (range 18 to 48). Research was conducted from March to June 2009. For the purpose of construction of the first version of the questionnaire, 67 statements (items) were developed. The statements were based on the relevant literature and were developed following rules and recommendations for questionnaire writing, and 36 items were chosen for final validation. Factor analysis was used to find out the factor structure of the questionnaire and to measure construct validity. ResultsThe final version of the questionnaire consisted of 29 items divided into a three-factor structure: factor I -positive attitude toward plagiarism (12 items); factor IInegative attitude toward plagiarism (7 items); and factor III -subjective norms toward plagiarism (10 items). Cronbach α was calculated to confirm the reliability of the scale: factor I -α = 0.83; factor II -α = 0.79; and factor III -α = 0.85. Correlations between factors were: -0.37 between I and II, -0.41 between I and III, and +0.31 between II and III.Conclusion Attitudes Toward Plagiarism questionnaire was developed, with good psychometric characteristics. It will be used in future research as a standardized tool for measuring attitudes toward plagiarism. BASIC SCIENCES doi: 10.3325/cmj.2010.51.195 BASIC SCIENCES 196 Croat Med J. 2010 51: 195-201 www.cmj.hrIn recent years, scientific misconduct and academic dishonesty have been in the focus of interest of the academic and scientific community (1-5). Academic misconduct is defined as any type of cheating that compromises the educational process and academic integrity of the institution. It includes plagiarism, fabrication, deception, corruption, and sabotage, while scientific misconduct usually includes fabrication, falsification, plagiarism, and other unethical behavior in professional scientific research (6-8). Plagiarism is the most frequent type of misconduct (9,10) and is defined as "unauthorized appropriation of another's work, ideas, methods, results or words without acknowledging the source and original author" (4). Self-plagiarism is widely considered to be a type of plagiarism, and it is defined as the inappropriate presentation of one's own published data or text as new and original. Among all types of misconduct in science and in an academic environment, plagiarism is consider to be the most vicious between peers, because it constitutes theft of intellectual property, which is the core achievement of intellectual work.The implementation of computer technology and the availability of scientific papers and books in electronic form have facilitated plagiarizing by allowing simple "copy-andpaste" procedures (11). On the other hand, the same technology has also enabled the development of plagiarism detection software (12,13).The extent of acade...

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Sa že takKo re la ci ja je sta tis tič ki pos tu pak za iz ra ču na va nje po ve za nos ti dvi ju va ri jabli. Vri jed no st ko re la ci je broj ča no se is ka zu je koe fi ci jen tom ko re la ci je, naj češ će Pear so no vim ili Spear ma no vim, dok se zna čaj no st koe fi ci jen ta is ka zu je vri jednoš ću P. Koe fi ci je nt ko re la ci je po ka zu je u ko joj su mje ri prom je ne vri jed nos ti jed ne va ri jab le po ve za ne s promje na ma vri jed nos ti dru ge va ri jab le. Pred znak koe fi ci jen ta ko re la ci je (+ ili -) go vo ri nam o smje ru po ve za nos ti. Pri li kom iz raču na va nja ko re la ci je naj češ će se pog r ješ ke od no se na uv je te za iz ra ču na va nje ko re la ci je, tu ma če nje koe fi ci jen ta i zna čaj no st ko re la ci je, vi so ke koe fi ci jen te ko re la ci je, pret pos tav lja nje uz roč no-pos lje dič ne ve ze, ja či nu po ve za nos ti (koe fi ci je nt de ter mi na ci je), te us po red bu dva koe fi ci jen ta ko re la ci je. Ključ ne ri je či: ko re la ci ja, Pear so nov koe fi ci je nt ko re la ci je, Spear ma nov koe fici jent ko re la ci je, koe fi ci je nt de ter mi na ci je, pog r ješ ka, sta tis ti ka Ab stra ctCor re la tion is a sta tis ti cal pro ce du re ap plied to cal cu la te as so cia tion be tween two va riab les. The va lue of cor re la tion is nu me ri cal ly shown by a coeffi cie nt of cor re la tion, mo st of ten by Pear so n's or Spear ma n's coeffi cie nt, whi le the sig ni fi can ce of the coeffi cie nt is expres sed by P value. The coeffi cie nt of cor rela tion shows the exte nt to whi ch chan ges in the va lue of one va riab le are corre la ted to chan ges in the va lue of the ot her. A si gn pre ce di ng the coeffi cie nt of cor re la tion (+ or -) in di ca tes the di rec tion of cor re la tion. The mo st freque nt er ro rs in cal cu la ti ng cor re la tion are re la ted to con di tio ns for cal cu la tion, in terpre ta tion of the coeffi cie nt and cor re la tion sig ni fi can ce, hi gh cor re la tion coeffi cien ts, as sum ption of cau sal re la tion ship, the stren gth of cor re la tion (coefficie nt of de ter mi na tion), and com pa ri son of two cor re la tion coeffi cien ts. Key wor ds: cor re la tion, Pear so n's cor re la tion coeffi cie nt, Spear ma n's cor re lation coeffi cie nt, coeffi cie nt of de ter mi na tion, er ror, sta tis ti cs Što tre ba zna ti ka da iz ra ču na va mo koe fi ci je nt ko re la ci je? What we need to know when cal cu la ti ng the coeffi cie nt of cor re la tion?Mar ti na Udovičić 1 , Kse ni ja Baždarić 1 , Li di ja Bi li ć-Zul le 1,2 , Mla den Pet ro več ki 1,3 1 Katedra za me di cin sku in for ma ti ku, Me di cin ski fa kul tet Sveu či liš ta u Ri je ci, Ri je ka