Shapes of distribution scores

Question 1

What is a frequency curve?

Answer 1

Drawing a continuous, smooth curve through the small steps of a histogram.

Question 2

What is the normal curve?

Answer 2

Symmetrical bell shape
Mean, mode and median are identical
Disparities between these means you have an unsymmetrical curve

Question 3

What are distorted curves?

Answer 3

Skewness and kurtosis

Question 4

What is skewness?

Answer 4

Negative skews: right leaning, mean and median smaller than mode, mean scores are to the left of the mode

Positive skews: left leaning, mean and median are bigger than mode, more scores are to the right side of the mode

Question 5

What is kurtosis?

Answer 5

Symmetrical curves may look like normal bell curves, but these are very steep or flat. There are 2 types: a shallow or steep curve.
No bearing on statistical techniques unlike skewness.

Positive values: curve is steep
Zero value: curve is middling
Negative value: curve is flat

Question 6

What is a bimodal distribution?

Answer 6

Twin peaks (two modes)

Question 7

What is cumulative frequency?

Answer 7

Frequencies cumulate
It gives the number of scoring e.g. there are 18 people who scored 2 or less in the test.
Diagrams and tables are useful for this so it isn’t misleading

Question 8

What are percentiles?

Answer 8

50th percentile is the median score
e.g. 10% of scores is equal to 7 or less than or 80% of sores are equal to 61 or less
Quick method of expressing a person’s score relative to others Produce a table of cumulative frequencies to calculate the percentiles