week 1: displaying data

Question 1

2 branches of statistical methods

Answer 1

descriptive

inferential

Question 2

what is descriptive

Answer 2

information is summarised so as to be more easily understood

Question 3

what is inferential

Answer 3

used to draw conclusions about regularities in the data

Question 4

what is a variable

Answer 4

a characteristic that can have different values
eg.
across people: gender, height, weight
within each person: height, weight, job satisfaction

Question 5

what is a value

Answer 5

a possible number or category that a score can have

eg. 1,2,3 female

Question 6

what is a score

Answer 6

a particular person’s value on a variable

eg. 3, 6, buddhist

Question 7

kinds of variables

Answer 7

Categorical (or nominal) variables

Numeric (or quantitative) variables

Question 8

Categorical/nominal variable

Answer 8

nominal (in name only)

variables in name only (1 = male, 2 = female

Question 9

types of Numeric/ quantitative variable

Answer 9

ordinal or rank-order variables
equal interval variables
ratio variables

Question 10

ordinal or rank-order variables

Answer 10

difference in magnitude implied
not equal intervals between ranks
ranks: e.g., place in class, order in a horse race

Question 11

equal interval variables

Answer 11

difference in magnitude implied
equal intervals are assumed
e.g., many test scores, temperature in Celsius/Fahrenheit

Question 12

ratio variables

Answer 12

all properties of ordinal and interval variables
plus a real zero
e.g., length, weight, time

Question 13

Frequency tables

Answer 13

shows how frequently each value of a variable occurs

Question 14

Grouped frequency tables

Answer 14

when there are many values

Question 15

Histograms

Answer 15

a way of graphing the information in a frequency table

a type of bar graph

Question 16

Frequency polygons

Answer 16

a line graph of the information in a frequency table

Question 17

Shapes of distributions

Answer 17

peaks
symmetry
thickness

Question 18

Number of peaks

Answer 18

1 peak: unimodal
2 peaks: bimodal
>2 peaks: multimodal
without any real peaks: rectangular

Question 19

symmetry

Answer 19

skewed distribution:

• if tail points to right positive skew
• if tail points to left negative skew

Question 20

thick or heavy tails

Answer 20

Leptokurtic
Platykurtic
‘normal’ distribution

Question 21

Leptokurtic

Answer 21

tails are thicker or heavier than normal curve

more easily recognised by top of curve being more peaked than normal curve

Question 22

Platykurtic

Answer 22

tails are thinner or lighter than normal curve