tailieunhanh - How to Display Data- P12

How to Display Data- P12:The best method to convey a message from a piece of research in health is via a fi gure. The best advice that a statistician can give a researcher is to fi rst plot the data. Despite this, conventional statistics textbooks give only brief details on how to draw fi gures and display data. | Relationship between two continuous variables 47 1 Measurements recorded include maternal age in years birthweight kilograms and the gestational age weeks ofthfbaby The correlations between all possible pairs of variables can be done by means of a correlationmatrixasin Table this thecorrelation coe fficientsare shown in a trianoutrrditolnysimiiarSo the charts inroad aliasesshowing the distances betwesn ptirsof Sowns. Xhs granhecalequivnlenti inCigLco Table Correlation matrixforgestation maternal ageandbirthweightfor 98 pre-term dabiet3 Gestation weeks Maternal age years Birthweight kg Gestation weeks Maternal age years Birthweight kg Figure Scatter diagram matrix showing each of the two-way relationship between maternal age birthweight and gestation in 98 premature 48 How to Display Data even better. Here it is clear that there is a strong correlation between birthweight and gestation age and norelation between either birthweight and maternal age or gestational age and maternal age. Regresj ion When it is plausible that the values of one variable exert an influence on the values of the other variable n leebuique too as regress san be used. In this chapter we shall only consider the simple case of a single continuous explanatoeyemdependenl variable and asingle continuous outcome dependent vasiabSeu Vuetlrrs methods of SisrUaymg Ac eusulte of s renue s-sion analysis with mvae iO an snr axutunaUotg vasiablr ate givun at Chaptea 7. Often it is of in merest Uo quanhUy the aelotionohep beUwuan the Pvo vauiaOaet and given apuetiuuliu valnoof she axplonatorvvaricbla tes anmdiuiOual to predict the valueofthrouehomanoeuablu. AuwlAaouneAtioipAf so Pole should be plotted usbnga scrUtsr uis ire .Hap ie a ibelOes roturiationie IsusrrnUiel that the explu ftoag veriabia tshe otieerrsting tun ioSS notice j is oeotteu on the X-axio anO tide eutcom evatiabltgheonebeinginflutnoed itplotOtd on the T-axts. Figure