Descriptive Statistics

Question 1

“Samples and Populations”

What is a population?

Answer 1

A group that contains ALL people or objects with characteristic in common

Question 2

“Samples and populations”

What is a sample?

Answer 2

researcher’s selection from the population

Question 3

“Samples and populations”

Why do researchers use sampling?

Answer 3

Cheaper
quicker
convenient

Question 4

“Samples and populations”

Before conducting research, what must the researcher insure?

Answer 4

Population is relevant to the sample

sample is truly representative of target population

Question 5

“Samples and populations”

What do we use descriptive statistics for?

Answer 5

Describing samples

Question 6

“Samples and populations”

Do you use inferential statistics for?

Answer 6

Generalising samples to wider populations

Question 7

“Measures of Central Tendency”

What are measures of central tendency?

Answer 7

Data that indicates the typical score in the data set

Question 8

“Measures of Central Tendency”

What are the three types of central tendency?

Answer 8

Mean
median
Mode

Question 9

“Measures of Central Tendency”

How to calculate the mean?

Answer 9

Add up all the sample Scores

Divide by how many scores are in the sample

Question 10

“Measures of Central Tendency”

How to calculate the median?

Answer 10

The middle value when sample scores are ordered

Question 11

“Measures of Central Tendency”

How to calculate the mode?

Answer 11

The most frequently occurring score

Question 12

“Measures of Central Tendency”

Which central tendency should be used When?

Answer 12

The mean is most frequently used.

You should use it when satisfied that scores Are typical of the sample

Question 13

“Measures of Central Tendency”

What is an issue with the mean? How can it be resolved?

Answer 13

Sensitive to extreme scores

Use the medium instead

Question 14

“Measures of Central Tendency”

What are outliers?

Answer 14

Extreme Scores in the Sample

Considerably higher or lower then other scores

Question 15

“Measures of Central Tendency”

How to find outlier on box plot?

Answer 15

School outside hinges of box

Number above Whiskers on box plot Show which score Is extreme

E.g. 10 equals tenth score is extreme

Question 16

“Measures of Central Tendency”

To do If there’s an outlier?

Answer 16

check data entered is correct

was there anything unusual that explains it in data collection
e.g participant did not finish

Question 17

“Measures of Central Tendency”

And you remove outliers from the data?

Answer 17

Yes if there is a legitimate reason - not if theres no reasoning
say that you removed it in report

Question 18

“Normal Distribution”

why do we look at normal distribution?

Answer 18

used to make assumption about a populations distribution

Question 19

“Normal Distribution”

What does normal distribution and require? (3)

Answer 19

1. Symmetrical about the mean
2. Tales meet x-axis at infinity
3. Bell shaped

Question 20

“Normal Distribution”

What are all the same normal distribution?

Answer 20

Mean medium and mode

Question 21

“Normal Distribution”

What is needed to plot normal distribution?

Answer 21

Function of the mean

Standard deviation

Question 22

“Normal Distribution”

What is normal distribution?

Answer 22

Distribution of scores that creates a bell shape

Question 23

“Normal Distribution”

how does normal distribution become “perfect”?

Answer 23

modes of mean, median and mode are all represented by the peak

Question 24

“Normal Distribution”

what does sample size have to do with normal distribution?

Answer 24

larger sample sizes represent distributions better because of the clearer peak

Question 25

“Variation or spread of distributions”

what is variation?

Answer 25

The the degree that the score of a variable is different to another

Question 26

“Variation or spread of distributions”

What is used to understand variation?

Answer 26

The range

Question 27

“Variation or spread of distributions”

How to calculate the range?

Answer 27

Take away the smallest value from the largest value

Question 28

“Variation or spread of distributions”

What does the range do?

Answer 28

Tells us about a overall range of scores

Question 29

“Variation or spread of distributions”

What is a limitation of the range?

Answer 29

Does not tell us about overall shape of distribution of the sample

Question 30

“Variation or spread of distributions”

What is standard deviation?

Answer 30

Square root of variance

Question 31

“Variation or spread of distributions”

what does standard deviation do?

Answer 31

Measures how much data deviates around the mean

Question 32

“Variation or spread of distributions”

why is SD Better than the range?

Answer 32

Indicates what is happening between two extremes

which tells the variation around the mean

Question 33

“Variation or spread of distributions”

why is standard deviation an important method?

Answer 33

Basis for most statistic techniques to analyse data

Question 34

“Variation or spread of distributions”

what is the problem with mean deviation?

Answer 34

Only measures Central tendency
half of deviations will be negative numbers
-When added they will become zero

Question 35

“Variation or spread of distributions”

How to resolve the problem with mean deviation?

Answer 35

Square each deviation from the mean
(Negative become positive)
Calculate the mean of squared deviations - This is variance

Question 36

“Variation or spread of distributions”

What is the issue with variance?

Answer 36

The squared deviation is not expressed in same unit as the original school
must square root variance to achieve this