The SPSS file urine.sav contains data on 79 urine specimens which were analysed in an effort to determine if certain physical characteristics of the urine might be related to the formation of calcium oxalate crystals.1 Calcium oxalate crystals in the urine are the most common constituent of human kidney stones. The variables are: CaOx Indicator of the presence or absence of calcium oxalate crystals. 0 for Absent and 1 for Present. gravity the density of the urine relative to water (specific gravity). pH the negative base 10 logarithm of the molar concentration, measured in units of moles per litre, of hydrogen ions (pH reading). osmo the osmolarity (mOsm). Osmolarity is proportional to the concentration of molecules in solution. cond conductivity (mMho). One Mho is one reciprocal Ohm. Conductivity is proportional to the concentration of charged ions in solution. urea urea concentration in millimoles per litre. calc calcium concentration in millimoles per litre. 

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