Booklet 3

Question 1

Name the measures of central tendency

Answer 1

Mean
Median
Mode

Question 2

Describe how to calculate each of the measures of central tendency

Answer 2

Mean- add all values and divide by the number of values
Median- put data in numerical order and find the middle piece of data
Mode- most common piece of data

Question 3

Name the measures of dispersion

Answer 3

Range
Standard deviation

Question 4

Describe each of the measures of dispersion

Answer 4

Range= largest piece of data-smallest piece of data
Standard deviation- the larger the SD, the greater the spread around the mean

Question 5

How do you calculate percentage increase?

Answer 5

1. calculate the increase
2. divide the increase by the original number
3. multiply by 100

Question 6

How do you calculate percentage decrease?

Answer 6

1. calculate the decrease
2. divide decrease by original number
3. multiply by 100

Question 7

Name the 4 types of graph

Answer 7

Bar chart
Histogram
Scatter gram
Pie chart

Question 8

Give advantages of the mean

Answer 8

Sensitive as considers every piece of data

Question 9

Give disadvantages of the mean

Answer 9

Can be affected by extreme scores
Sometimes value doesn’t make sense eg 2.4 children

Question 10

Give advantages of the median

Answer 10

Not affected by outliers

Question 11

Give disadvantages of the median

Answer 11

Not as sensitive as the mean- doesn’t include all values
Can be unrepresentative in small data sets

Question 12

Give advantages of the mode

Answer 12

Less influenced by extreme values
Sometimes makes more sense than the mean

Question 13

Give disadvantages of the mode

Answer 13

May be multiple modes
Doesn’t consider all data
Mode could be an outlier

Question 14

Give advantages of the range

Answer 14

Easy to calculate
Less time consuming
Less prone to error

Question 15

Give disadvantages of the range

Answer 15

Vulnerable to distortion by extreme values
Doesn’t show data in relation to the mean

Question 16

Give advantages of standard deviation

Answer 16

More sensitive as includes all values rather than just highest and lowest
Allows interpretation of individual scores

Question 17

Give disadvantages of standard deviation

Answer 17

More complicated to calculate
More time consuming
More prone to errors
Less meaningful if there isn’t a normal distribution

Question 18

When are bar charts used?

Answer 18

Discrete data- divided into categories
Categories on x-axis
Mean or frequency on y-axis
BARS DO NOT TOUCH

Question 19

When are histograms used?

Answer 19

Data is continuous
Scores on x-axis
Height of column shows frequency of values
BARS MUST TOUCH

Question 20

When are scattergrams used?

Answer 20

Used when looking for a relationship or correlation between variables
Data from one variable on one axis, other variable on other axis
Plot an ‘x’ where two variables meet
Pattern of plotted points reveals correlation- positive, negative or no correlation

Question 21

When are pie charts used?

Answer 21

Discrete, non continuous data
Shows the percentages that contribute to the whole sample

Question 22

Describe normal distribution

Answer 22

Standard deviation can be displayed as a normal distribution curve
Graph is symmetrical
50% of scores fall above mean
50% of scores fall below mean
Around 68% of scores fall within 1 standard deviation of the mean
Around 95% of scores fall within 2 standard deviations of the mean

Question 23

Describe skewed distribution

Answer 23

When results are not evenly distributed around the mean
Negative skew- when the mean is the lowest value
Positive skew- when the mean is the highest value

Question 24

Name the levels of measurement

Answer 24

Nominal
Ordinal
Interval

Question 25

What is nominal data?

Answer 25

Can be placed into separate categories Usually involves counting the frequency of behaviours

Question 26

What is ordinal data?

Answer 26

Can be ranked/ordered but the difference between values is not equal/consistent

Question 26

What is interval data?

Answer 26

Has a standardised measurement eg time,weight so difference between values is equal and consistent

Question 27

Name the statistical tests and the acronym

Answer 27

Carrots Should Come Mashed With Suede Under Roast Potatoes Chi-squared, sign test, chi-squared, mann-whitney, wilcoxon, spearman's rho, unrelated t-test, related t-test, pearson's r

Question 28

What is the level of significance?

Answer 28

The probability at which the results of an experiment occurred by chance Also known as P value = 5%

Question 29

How do you work out the correct critical value?

Answer 29

1. one or two tailed test? 2. number of p's/n value/degrees of freedom 3. level of significance- usually 5%

Question 30

How do you calculate the sign test?

Answer 30

1. use +/- to show whether the values have increased or decreased, cross out any scores with no difference 2. count how many of each sign 3. identify the number of the least frequent sign

Question 31

Type 1 error

Answer 31

False positives Researcher claims there has been a significant difference when there isn't one Wrongly rejects null hypothesis and accepts experimental hypothesis Caused by significance level being too lenient (p<0.1)

Question 32

Type 2 error

Answer 32

False negatives Researcher claims there was no significant difference when there was Wrongly rejects experimental hypothesis and accepts null hypothesis Caused by significance level being too harsh (p<0.01)