RESEARCH METHODS: measures of central tendency and dispersion

Question 1

What are measures of central tendency?

Answer 1

The general term for any measure of the average value in a set of data.

Question 2

what is the mean and how is it calculated?

Answer 2

The mean is the arithmetic average calculated by adding up all the values in the set of data and dividing by the number of values.

Use if there are no outliers

Question 3

What is the median and how is it calculated?

Answer 3

The central value in a set of data when values are arranged from lowest to highest.

Use if there is an outlier (extreme value) in data set.

Question 4

What is the mode and how is it calculated?

Answer 4

The most frequently occurring value in a set of data

Use if the data is in categories or there are several repeated numbers.

Question 5

What is measures of dispersion?

Answer 5

Measures of dispersion is based on the spread of scores. It is how far scores vary and differ from one another

Question 6

What is the range and how is it calculated?

Answer 6

Taking the lowest value away from the highest value and adding one.
(17-5)+1=13

Question 7

evaluate the mean?

Answer 7

+ considers the average of all numbers in dataset.
- the main score can be distorted by extreme values in the dataset. If therefore may not be an accurate average score.

Question 8

evaluate the mode?

Answer 8

+ it is unaffected by extreme scores
- can be affected by the change in one score. This means it is unrepresentative.

Question 9

evaluate the median?

Answer 9

+ calculates the middle value within the data set.
- it only takes into account one or two values and therefore doesn’t represent the whole dataset.

Question 10

Evaluate the range?

Answer 10

+ easy to calculate
- it only takes into account the two most extreme values, which may be unrepresentative of the dataset as a whole.

Question 11

what is standard deviation?

Answer 11

Calculate the amount of variations within the data set. It tells us how fast cause deviate from the mean. The larger the standard variation the greater the spread within a set of data.

Question 12

evaluate standard deviation?

Answer 12

+ the most accurate and precise measures of dispersion.
- as all values are included it can be distorted by a single extreme value.

Question 13

What are some examples of graphical representations?

Answer 13

Table, bar chart, histogram, scattergraph.

Question 14

what does a table represent?

Answer 14

It is the basic method of summarising information. It usually includes a summary paragraph beneath the table.

Question 15

what is a bar chart and what does it represent?

Answer 15

It is used when data is divided into categories (discrete data). Bars are separated to show that we are dealing with separate conditions.

Question 16

what is a histogram and what does it represent?

Answer 16

Shows the distribution of continuous data. The bars touch.

Question 17

what is a scattergram and what does it represent?

Answer 17

It is used to plot correlations and share relationships between co-variables.

Question 18

what is normal distribution?

Answer 18

A symmetrical spread of frequency data that forms a bell shaped pattern. The mean, mode, median are located at the highest peak.

Question 19

What are skewed distributions?

Answer 19

Bird of frequency data that is not symmetrical, where the data clusters to an end.

Question 20

what is a positive skew?

Answer 20

Most of the distribution is concentrated towards the left the graph, resulting in a long tail on the right.

Question 21

What is a negative skew?

Answer 21

Most of the distribution is concentrated towards the right of the graph, resulting in a long tail on the left.