Ch02 Frequency Distributions

Question 0

Skewed Distribution

Answer 0

scores tend to pile up toward one end of the scale and taper off gradually at the other end

positively skewed = most at front end
negatively skewed = most at back end

\+ = tail points to right
- = tail points to left

Question 1

Symmetrical Distributoon

Answer 1

symmetrically distributed graph

not much else to say at this point

Question 2

Percentile (Rank)

Answer 2

percentage of individuals in the distribution with scores equal to or less than the particular value

Question 3

Cumulative Frequency (CF)

Answer 3

number of individuals at or below a value

Question 4

Cumulative Percentages

Answer 4

percentage of individuals who are located in and below each category

c% = ( cf / N ) * 100% where N = total #

Question 5

Interpolation

Answer 5

if percentiles are upper real limits (and ranks are percentages) it is possible to determine some percentiles and percentile ranks from an FDT

(X=4, c%=95% -> 95th percentile = 4.5)

Question 7

Grouped Frequency Distribution Table (FDT)

Answer 7

around 10 intervals (if more make class intervals)

width of interval is simple number

bottom score of an interval should be a multiple of its width (w = 5, bot. score = 10)

all intervals same width and covers range with no gaps

Question 9

Frequency Distribution Graph

Answer 9

scores are on the X-axis and frequency is on the Y-axis

Question 10

Histogram

Answer 10

for interval / ratio scores (no gaps)

bars extend to the real limits of the score, so all bars touch

Question 11

Polygon

Answer 11

dot is placed above the midpoint of each score / class interval so height of dot = frequency

connect all dots

Question 12

Bar Graph

Answer 12

for ordinal / nominal scales

there are gaps between bars