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Published byHollie Thomas Modified over 9 years ago
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1 WHY WE USE EXPLORATORY DATA ANALYSIS DATA YES NO ESTIMATES BASED ON NORMAL DISTRIB. KURTOSIS, SKEWNESS TRANSFORMATIONS QUANTILE (ROBUST) ESTIMATES OUTLIERS EXTREMS YES NO QUANTILE (ROBUST) ESTIMATES WHY ? CAN WE REMOVED THEM ? DO DATA COME FROM NORMAL DISTRIBUTION? TRANSFORMATIONS
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2 METHODS OF EDA Graphical: dot plot box plot notched box plot QQ plot histogram density plots Tests: tests of normality minimal sample size
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3 DOT PLOT
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4 BOX PLOT lower quartil upper kvartil fence outer inner fence inner outer interquartile range (H) číselná osa median
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5 NOTCHED BOX PLOT interval estimate of median RFRF
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6 Q-Q PLOT X: theoretical quantiles of analysed distribution Y: sample quantiles ideal coincidence of sample values and theoretical distribution measured values
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7 Q-Q GRAF
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9 Q-Q plot right sided – skewed to left left sided – skewed to right platycurtic („flat“) leptocurtic(„steep“)
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12 HISTOGRAM
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13 HISTOGRAM correct width of interval:
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14 HISTOGRAM – kernel density function
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15 TRANSFORMATION Aim of transformation: reduction of variance better level of symmetry(normality) of data Transformation function: non-linear function monotonic function
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16 TRANSFORMATION – basic concept
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17 TRANSFORMATION – logaritmic transformation
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18 TRANSFORMATION – power transformation
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19 TRANSFORMATION – Box-Cox
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20 TRANSFORMATION – Box-Cox
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21 TRANSFORMATION– estimate of optimal logarithm of likelihood function for various values of optimal interval estimate of parameter = 1 is not included in interval estimate of. It means that transformation will be probably successful 1.00 maxLF– 0,5* quantile 2
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