Qual/Quant Analysis

Question 1

3 Steps in the Statistical Process

Answer 1

1) Collect Data
2) Describe & Summarize the Distribution
3) Interpret - draw general conclusion for the pop on the basis of the sample

Question 2

Nominal Data

Answer 2

Mutually Exclusive groups, lack intrinsic order.

Zoning classification, social security numbers, sex.

Question 3

Ordinal Data

Answer 3

Ordered implying a ranking of observations. Values are meaningless - rank is important.

Letter grades, response scales on a survey 1-5, suitability for development

Question 4

Interval data

Answer 4

Data with ordered relationship where the difference between scales has meaning.

Temperature. Diff between 40 and 30 degrees is the same as 30 and 20 but 20 degrees is not twice as cold as 40 degrees.

Question 5

Ratio Data

Answer 5

Gold standard of measurement. Absolute and relative difference have meaning.

Distance measurement. 40 - 30 miles is the same difference as 30-20 miles and 40 miles is twice as far as 20 miles.

Question 6

Quantitative Variables

Answer 6

Variables where numerical value is meaningful.

Interval or ratio measurement.

HH income, level of pollution in river

Question 7

Qualitative Variables

Answer 7

Variables where numerical value is not meaningful.

Nominal/Ordinal measurement.

Zoning classification.

Question 8

Continuous Variables

Answer 8

Infinite number of values.

Positive & negative.

Most measurements in physical sciences yield continuous variables.

Question 9

Discrete variables

Answer 9

Finite number of distinct values.

Accidents per month - can’t be negative.

Question 10

Binary/dichotomous variables

Answer 10

Special case of discrete variables which can only take on two values - 0/1 typically.

Question 11

Descriptive variables

Answer 11

Describe the characteristics of the distribution of values in a population or sample.

Ex: on average, AICP test takers in 2018 are 30 years old

Question 12

Inferential Statistics

Answer 12

use probability to determine characteristics of a pop based on a sample.

Question 13

Distribution

Answer 13

the overall shape of observed data.

Ordered table, or histogram, or density plot

Question 14

Normal or Gaussian Distribution

Answer 14

the bell curve.

Distribution is symmetric. The spread around the mean can be related to the proportion of observations.

More specifically, 95% of the observations that follow a normal distribution are within two standard deviations from the mean

Question 15

Symmetric distribution

Answer 15

equal number of observations are below and above the mean

Question 16

Central tendency

Answer 16

Typical or representative value for the distribution of observed values

Question 17

Coefficient of Variation

Answer 17

the relative dispersion from the mean by taking the standard deviation and dividing by the mean.

Question 18

z-score

Answer 18

This is a standardization of the original variable by subtracting the mean and dividing by the standard deviation.

The z-score in effect transforms the original measure into standard deviation units.

Question 19

inter-quartile range or IQR.

Answer 19

Alternative measure of dispersion.

Breaks things into quartiles.

This is visualized in a box plot (also called box and whiskers plot).

Question 20

confidence interval.

Answer 20

this constitutes a range around the sample statistic that contains the population statistic with a given level of confidence, typically 95% or 99%.