Statistics

Question 1

What is Descriptive statistics?

Answer 1

Summarises a given data set (graphically or numerically). Aim to provide a shorthand description of large amounts of data.

Question 2

What is Inferential statistics?

Answer 2

Used to draw conclusions about a population from studying a sample.

Question 3

define a Population

Answer 3

A large group e.g All students from University.

Question 4

define a Sample

Answer 4

A small number taken from a large group.

Question 5

What are variables?

Answer 5

Variables are characteristics of individuals, objects or events that can take on different values or amount. e.g blood pressure, weight, age, sex.

Question 6

What are observations?

Answer 6

Outcomes (value) of the measurement or registration. e.g 120/60 mmHg, 70kg, 35 years, male etc.

Question 7

Types of Variables are:

Answer 7

Qualitative (categorical) and Quantitative (numerical)

Question 8

3 Different types of qualitative variables are:

Answer 8

BINARY- Two distinct categories. (e.g male and female).

NOMINAL - names or categories. (single, married).

ORDINAL - Data is ordered in terms of degree (e.g social class 1-5).

Question 9

2 different types of quantitative variables:

Answer 9

CONTINOUS - (Measurable) it is a measurement on a continuous scale. e.g blood pressure 143.4 mmHg.

DISCRETE- (COUNTABLE) Ir can only take a limited number of discrete values. For example number of children in a family 2 or 3.

Question 10

How do you summarise qualitative (categorical) data?

Answer 10

• Count the number of observations. These counts are called frequencies.

Question 11

How do you present qualitative (categorical) data?

Answer 11

• Using numbers (table): Frequencies (e.g male and female)

- Using graphs = Pie chart & Bar chart.

Question 12

What are the length of bars in a bar diagram proportional to?

Answer 12

Frequency

Question 13

What is a section in a pie chart proportional to?

Answer 13

Percentage

Question 14

What are 2 ways to summarise numerical data?

Answer 14

Using Numbers - measures of central tendency and variation.

Using graphs/ tables - histograms and frequency polygon.

Question 15

What is Ordered Array?

Answer 15

It is a list of the observations in order of the increasing magnitude from the lowest value to highest.

Also makes it easier for more calculation and further organisation to be done.

Question 16

What does the decision maker or scientist get a feel for when looking at ordered array?

Answer 16

The magnitude of the data.

Question 17

Other than ordered array, how else can the data be classified?

Answer 17

Frequency distribution. (Look for patterns in the data set). However can make a long table of data and make it complicated.

Question 18

After ordered array and frequency distribution, Whats a further grouping method of data?

Answer 18

Class Intervals.

Question 19

What are classes?

Answer 19

They are groups the data is organised into.

Question 20

What are class limits?

Answer 20

They are the smallest and largest observations in each class. Therefore, each class has two limits a lower and upper.

Question 21

Classifying the data with too few intervals results in….

Answer 21

Excessive loss of information.

Question 22

Classifying the data with too many intervals results in…

Answer 22

Defeating the purpose of summarisation.

Question 23

How can frequency distribution be explained as?

Answer 23

How frequent certain things happen within a set of data.

Question 24

How can frequency distribution be presented graphically?

Answer 24

Histogram

Question 25

Differences between a Bar Chart and Histogram

Answer 25

Bar chart =

• Categorical Data
• Bars in a bar chart are not contiguous

Histogram=

• Numerical Data
• Bars of a histogram are contiguous.

Question 26

When testing for normality what result indicates normality?

Answer 26

a non significant result (sig value of greater than 0.05) indicates normality.

Question 27

What are tests for normality?

Answer 27

Kolmogorov-smirnov (K-S) and shapiro-wilk (S-W).

Question 28

When are scewness values significant?

Answer 28

1.96 or less than -1.96 are significant