Variables and Formulas

Question 1

Deviation from the mean:

MeanpHQ = (ΣN i=1 pHQi) / N

Answer 1

pHQi — is the overall exterior housing quality of the ‘i’th house (e.g., 100 Riverside Drive) as a percentage above or below normal.

N — total number of houses in the population

ΣN i=1 — (pronounced as big sigma, with eye running from one to en) indicates that we will be adding up numbers from the first (i=1) one to the final (i=N) one.

Two different symbols to represent a Mean or Average.

X̅ — (pronounced as exbar) is the symbol for the Mean of a Sample, with n = number of cases

μ — (pronounced as mew) is the symbol for a Population Mean, with N = the number of cases.

Question 2

MdpHQ = ((N + 1) / 2)

Answer 2

N = the number of values in an ordered data set

MdpHQ = ((N + 1) / 2) just tells you what value (number in the order) that is the middle value.

Question 3

( xi - X̅) or (pHQi - μpHQ)

Answer 3

How far an individual or raw percentage in a distribution deviates from the mean of the
distribution.

Question 4

ΣN i=1 (pHQi - μpHQ) = 0

Answer 4

The summation of these deviations from the mean will always equal zero.

Question 5

Mean Deviation:

( ΣN i=1 | pHQi μpHQ | ) / N

Answer 5

Sum their absolute values, and then divide the sum by the number of cases or houses in the distribution.

Where the straight up and down || brackets indicate to take the absolute value of a calculated number inside them by discarding its possible negative sign.