Descriptive Statistics Limdep

Reset $
READ; File=C:\Users\FAUSAC\Desktop\claudio3.XLS;Format=xls$
List; numvisit,ingreso,ctv,sexo,edad,educa $

? Now let's compute some descriptive statistics using LIMDEP's canned procedures.Note that the Output option gives particular output that you want, including a correlation matrix. The Quantile and Plot option calls for quantiles and plots which are used in testing for normality.An S shaped curve in the plots suggests non-normality, but this test may not be very reliable with small samples. The All option calls for skew and kurtosis statistics which is another way of checkingfor non-normality. Skew and kurtosis should both be near zero for a normal distribution. */

Dstat; Rhs=numvisit,ingreso,ctv,sexo,edad,educa ; Output=6 ; Quantiles; Plot; All $

? You can alsoconduct a more formal test for normality, the Bowman and Shenton normality test. This test is compared with a Chi-Squared distribution with two degrees of freedom. Let's compute the test statistic forthe variable US above. */

Create; S3=Dev(ctv)^3/N-1 ; S4=Dev(ctv)^4/N-1 $
Calc; List ; C=N*(Sum(S3)/(6*Sdv(ctv)^3) + Sum(S4)/(24*Sdv(ctv)^4)) $

? Below find the critical value for theChi-Squared distribution for 2 degrees of freedom. Compare this to the test statistic above.*/

Calc; List; Ctb(.95,2) $

? Below test the exact significance level of the normality test above using theChi-Squared distribution. */

Calc; List; Cprob=1-Chi(C,2) $

? Now lets compute the mean of US using least squares. Note that this approach does not enable you to obtain the variance.*/

Minimize;labels=mu; Start=130; Fcn=(ctv-mu)^2; Alg= Newton $

? You could also use the regression procedure to do this as follows. This approach allows you to obtain the variance (S.D. squared), but there isno standard error on the variance estimate. */

Regress; Lhs=ctv; Rhs=One $

? Now lets compute the mean and variance of US using maximum likelihood (MLE). */

Maximize; labels=mu,Sig2;...