Statistics: Unlocking the Power of Data Lock5ECMT1010: Business and Economic Statistics A (semester 2, 2013) Lecturer: Simon Kwok
Statistics: Unlocking the Power of Data Lock5Announcements Online homework 7: due at 5pm tomorrow (this Wednesday). Online homework 8: to be released after 1pm on 10 October (this Thursday).
Statistics: Unlocking the Power of Data Lock5Outline Density curves (Section 5.1) Normal distribution (Section 5.1) Finding normal probabilities (technology) Finding normal endpoints (technology) Standard normal Central limit theorem (Section 5.2) Confidence interval using a normal distribution Hypothesis test using a normal distribution
Statistics: Unlocking the Power of Data Lock5Some Bootstrapand Randomization Distributions slope(thousandths)-60-40-200204060Dot Plotr-0.4-0.20.00.20.40.6Nullxbar98.298.398.498.598.698.798.898.999.0Diff-4-3-2-101234xbar26272829303132Dot PlotSlope :Restaurant tips Correlation: Malevolent uniforms Mean :Body Temperatures Diff means: Finger taps Mean : Atlanta commutes phat0.30.40.50.60.70.8Proportion : Owners/dogs All bell-shaped distributions
Statistics: Unlocking the Power of Data Lock5Density Curve A density curve is a theoretical model to describe a variable’s distribution.Think of a density curve as an idealized histogram, where: (1) The total area under the curve is one. (2) The proportion of the population in any interval is the areaover that interval.
5Density for Bootstrap Means for Atlanta Commutes What proportion are between 30 and 31?
Statistics: Unlocking the Power of Data Lock5Normal Distribution A normal distribution has a symmetric bell-shaped density curve.