Chapter 5 Exploring Data with Graphs

Question 1

Bar Chart (4)

Answer 1

A graph in which:

1. a summary statistic (usually the mean) is plotted on the y-axis
2. against a categorical variable on the x-axis (e.g. groups of people)
3. The value of the mean for each category is shown by a bar
4. Different-coloured bars may be used to represent levels of a second categorical variable.

Question 2

Boxplot (Box-Whisker Diagram) (5)

Answer 2

1. A graphical representation of some important characteristics of a set of observations.
2. At the centre of the plot is the median,
3. which is surrounded by a box,
4. the top and bottom of which are the limits within which the middle 50% of observations fall (the IQR).
5. Sticking out the top and bottom of the box are two whiskers which extend to the highest and lowest extreme scores, respectively.

Question 3

Chart Builder (1)

Answer 3

1. Window to build a chart in SPSS

Question 4

Chart Editor (1)

Answer 4

1. Window to edit a chart in SPSS

Question 5

Chartjunk (2)

Answer 5

1. Superfluous material

2. Distracts from the data being displayed on a graph

Question 6

Density Plot (4)

Answer 6

1. Similar to a histogram
2. except that rather than having a summary bar representing the frequency of scores,
3. it shows each individual score as a dot.
4. They can be useful for looking at the shape of a distribution of scores.

Question 7

Error Bar Chart (5)

Answer 7

1. A graphical representation of the mean of a set of observations
2. that includes the 95% confidence interval of the mean.
3. The mean is usually represented as a circle, square or rectangle at the value of the mean (or a bar extending to the value of the mean).
4. The confidence interval is represented by a line protruding from the mean (upwards, downwards or both) to a short horizontal line representing the limits of the confidence interval.
5. Error bars can be drawn using the standard error or standard deviation instead of the 95% confidence interval.

Question 8

Line Chart (5)

Answer 8

1. A graph in which a summary statistic (usually the mean) is plotted on the y-axis
2. against a categorial variable on the x-axis.
3. The value of the mean for each category is shown by a symbol,
4. and means across categories are connected by a line.
5. Different-coloured lines may be used to represent levels of a second categorical variable.

Question 9

Regression Line (2)

Answer 9

1. A line on a scatterplot representing the regression model

2. of the relationship between the two variables plotted.

Question 10

Scatterplot (2)

Answer 10

1. A graph that plots values of one variable against the corresponding values of another variable
2. (and the corresponding values of a third variable can also be included on a 3D scatterplot).