Statistics Ch 3 – Measure Something
*Chapter 3:Statistics – measure something.Is a value, is a dataThe process of measuring, is a methodDescriptive statistics: formulaStatistical inference: How good is going to be the forecasts or estimates with our limited dataPopulation: All the possible outcomes available. What is the parameter of the populationSample: part of the population. Use the statisticOrdinal scales: not organize or same difference values between the categories.Interval scales: doesnt have a true zero. Because 0 degrees is a 0 but doesn’t mean that temperature doesn’t exist. We are going to use the Ratio Scales. Relative measure – Rate of Return“Ex ante” before the fact”With the ex post data we have to try to get the ex ante data.Equal average formula in excel for Population arithmetic mean.Difference between Population arithmetic mean and Sample arithmetic mean: is the same formula but in one use population (bigger) or sample (little)Deviation or deviation from the mean: dispersion. Something relate with the risk. Regular Mean: (1+2+3)/3. Add up all the observations.
Weighted arithmetic mean: Xw= (1/6)(1)+(1/2)(2)+(1/3)(3)=(2)(1/6). Geometric mean: multiple all the observations and rain cuadrada. Noun of the Xi could be negative: Xi>=01+R=P1/P0 (Price relative)1+R is a price relativeFor historical data is better Geometric Mean0        1        2100        50        75Mean= (50-100)/100=50% ; (75-50)/50=50% ; R=(-50%+50%)/2=0GM= “raiz(1+R1)*(1+R2)” -1 ; ”raiz(0.5)*(1.5)” -1 = -13.39%