Maths and Excel exercise Essay Example | Topics and Well Written Essays - 750 words

Maths and Excel exercise - Essay Example The horizontal dotted line indicates that the blue curve and the green curve have the same maximum. The vertical dotted lines indicate the maxima for the three curves, respectively. g) The weight of the heads of household appears to be normally distributed. Wages however are extremely skewed, resulting in many households with low wages and a few with high wages. The education level is a symmetric, discrete distribution, with both highly educated and less educated heads of households being rare. Since weight is the only symmetric distributed variable in the table, only in its case are the sample mean and median close to each other. Another indication that weight is indeed normally distributed is the proximity of the actual percentages of weights falling within the three given intervals to the empirical percentages. This is because the empirical percentages are calculated assuming normality of the data. An interesting observation is that the size of the 95% confidence interval for clothing and recreational expenses is actually much higher than that of more basic expenses such as food and housing. It is also interesting to note that clothing and recreational expen ses are more tightly correlated with net income than food and household expense are, as indicated by the marginally higher correlation coefficient of TOTEXP2 with FINC than TOTEXP1 with FINC. ... TOTEXP2 10.82 109.38 Note: 95% Confidence Interval has been calculated for the left tail, since all 3 variables show skewed distributions. e) Correlation coefficient r = 0.9927 Correlation coefficient r = 0.9979 f) The regression equation for TOTEXP1 Vs FINC is y = .59x + 1.5, while the regression equation for TOTEXP2 Vs FINC is y = .16x + .088 g) The weight of the heads of household appears to be normally distributed. Wages however are extremely skewed, resulting in many households with low wages and a few with high wages. The education level is a symmetric, discrete distribution, with both highly educated and less educated heads of households being rare. Since weight is the only symmetric distributed variable in the table, only in its case are the sample mean and median close to each other. Another indication that weight is indeed normally distributed is the proximity of the actual percentages of weights falling within the three given intervals to the empirical percentages. This is because the empirical percentages are calculated assuming normality of the data. An interesting observation is that the size of the 95% confidence interval for clothing and recreational expenses is actually much higher than that of more basic expenses such as food and housing. It is also interesting to note that clothing and recreational expens es are more tightly correlated with net income than food and household expense are, as indicated by the marginally higher correlation coefficient of TOTEXP2 with FINC than TOTEXP1 with FINC. One possible interpretation is that spending on less basic needs is more constrained by income than spending on more basic needs