STAT151 Chapter Notes - Chapter 5: Standard Deviation, Unimodality

• School: University of Alberta
• Department: Statistics
• Course: STAT151
• Professor: Omar Rivasplata

Document Summary

Chapter 5- the standard deviaion as a ruler and the normal model. Use the standard deviaion to judge how unusual a value is by how far it is from the mean. Subtract the mean and divide by s (standard deviaion) The result is the standardized value, also called the z- s scores. Negaive z-score means that the value is below the mean while a posiive z-score is above the mean. E. g. z-score=2, means that the value is 2 standard deviaion above the mean. Standardizing helps compare values that are measured on diferent scales with diferent units. Adding/ subtracing a constant to each value: measures of posiion (center, perceniles, min, max) will increase/ decrease by the same constant, but leaves the measures of spread (range, iqr, standard deviaion) unchanged. Muliplying/ dividing all data values by a constant: Measures of posiion and measures of spread are muliplied/ divided by the same constant.