Descriptive statistics (MOCT/MOS)

Question 1

Define measures of central tendency.

Answer 1

A method to find out the average score from a data set using (mode, median, mean)

Question 2

Define mean

Answer 2

Average value in a data set

Question 3

How do you calculate mean?

Answer 3

Add scores up
Divide by the number of ppts

Question 4

Mean- Strengths

Answer 4

most robust as it uses all the scores to provide an average

Question 5

Mean Weakness

Answer 5

Can be skewed by exteme low/high scores (anomalies)
Shouldn’t be used when there are extreme scores

Question 6

Why is the mean a useful calculation?

Answer 6

Data summary, comparisons, predictive value

Question 7

Define mode

Answer 7

Most frequent value or category in a data set

Question 8

Mode- Strengths

Answer 8

Not skewed by anomalies
Useful to show the most popular value

Question 9

Mode- weakness

Answer 9

Less robust- Only uses the most frequent score- ignoring all other data
Can’t be used if theres more than 1 mode

Question 10

why is the mode a useful calculation?

Answer 10

used for categorical data. Where data is divided into categories

Question 11

How to work out mode?

Answer 11

Put scores in rank order
Identify the most frequent value

Question 12

Why shouldn’t the mode be used when there is more than 1 mode?

Answer 12

There are more than 1 categories that occur within the same highest frequency. So the mode doesn’t provide a single unique value to describe the mode

Question 13

Define median

Answer 13

The middle value of a data set. when arranged in acceding/descending order

Question 14

Median- strengths

Answer 14

Not skewed by extreme high or low values (anomalies)

Question 15

Median- weakness

Answer 15

less robust. Only uses middle scores ignoring data that is v high/low

Question 16

Why is the median a useful calculation?

Answer 16

useful for data where the order matters, like when you’re ranking things

more reliable when you don’t have many numbers to work with.

Question 17

How to work out median?

Answer 17

Put scores in rank order and identify middle value (divide by 2 if there are 2 medians)

Question 18

Define measures of spread

Answer 18

Describes how spread out/varied the values in a data set are through calculations of range, and standard deviation.

(How much the individual values in a data set differ/vary from each other)

Question 19

Define range

Answer 19

Refers to the difference between the higher and lowest values in a data set.

Question 20

How is the range calculated?

Answer 20

1. Finding the largest and smallest value in a data set.
2. Subtracting the smallest from the largest
3. Add 1

Question 21

Why is there 1 added to the range?

Answer 21

To account for the fact that the scores are often rounded up and down in research. And make sure both highest/lowest values are included in the range.

Question 22

Range- strengths

Answer 22

Quick, and easy to calculate

Question 23

Range weakness

Answer 23

Less robust as it only uses highest and lowest scores. (Which could be skewed by anomalies) that aren’t typical of the majority of ppts.

Question 24

Standard deviation definition

Answer 24

Shows the amount of variation/dispersion of individual data points from the mean of a dataset.

Question 25

Groups with scores that are more spread out….

Answer 25

Have larger standard deviations

Question 26

Groups with closely clustered scores have….

Answer 26

Smaller deviations

Question 27

What does it mean if the standard deviation of 2 groups are similar?

Answer 27

Not much variation/ They have similar variations around the mean

Question 28

Standard deviation- strength

Answer 28

More robust- uses all scores to show how far a group of scores vary from the mean

Not influenced by extreme scores at either end of the data set

Question 29

Standard deviation- weakness

Answer 29

Time consuming to calculate

Question 30

When are bar charts used?

Answer 30

Used for categorical, ordinal data, and frequency distributions

Question 31

Describe how to plot the dv and iv on bar charts.

Answer 31

Levels of the iv= X axis
The dv=Y axis

Question 32

When are histograms used?

Answer 32

To show the pattern of a whole data set and distribution of numbers/scores (how numbers are spread out eg height/age)

Question 33

Describe how to plot scores on a histogram

Answer 33

The dv: is plotted on the x axis (categorises)
The frequency of each score: is plotted on the y axis

Question 34

Scattergram definition

Answer 34

The results of a correlational study are displayed on a scatter gram.

Question 35

Describe how to draw a scatter gram

Answer 35

1. Plot points
2. Draw a line
3. Line of best fit

Question 36

How does a strong correlation look like on a Scattergram?

Answer 36

Data points are close to the line

Question 37

How does a weak correlation look like on a Scattergram?

Answer 37

Data points are more spread out