8.5 measures of dispersion + presentation of quantitative data

what are the 2 measures of dispersion

range and standard deviation

what is measures of dispersion?

describe how spread out the data is

what does a high SD mean?

tells the RSer that individual scores are far away from the mean, high ptp variation

meancmay not be reliable

what does a low SD mean?

much less variation from mean, more reliable

range ao3

+ easy to calculate (largest - smallest)

- sensitive to outliers, makes it misleading

- not sensitive enough to comparevariation across data

standard deviation ao3

+ takes account all data, making it accurate of variability

+ less affected by outliers than the range due to using all scores

- complex to calculate, and requires multiple steps

how do u find percentage?

part / whole x100

what are the types of presentation and display for quaNtitative data?

scattergraphs, bar charts, histogram, tables, graphs

what is bar charts used for?

when the data is comparing the means of two groups, or frequency data for categories

what are scattergrams used for?

represent correlational data. there must be two scores for each ptp

when is a histogram used?

show the distribution of data, showing continuous data and ordinal

spots normal or skewed distributions

describe two types of tables and what they represent

• frequency table, display for histogram graphs. only summarises one table

• contingency table is used to represent the relationship between two or more categorical variables