Ch. 13

How can the appearance of day-to-day variability be reduced? What are the cautions (3) worth noting about aggregating data points into blocks?

-By plotting the data in blocks of time rather than on a daily basis. -First, aggregating data points onto block reduces the number of data points in the graph for each of the phases. -Second and related, aggregating days into blocks will reduce the number of data points and could undermine the key purposes of collecting continuous data. -Third, the actual data plotted in blocks can distort performance. Plotting data on a daily basis rather than in blocks is not inherently superior or more veridical.

What does a change in level usually refer to?

-Changes in level across phases, that is, the discontinuity or shift in the data at each point that the experimental condition is changed. -To the difference in the last day of one phase and the first day of the next.

What is the obvious advantage of the simple line graph and what does it represent? What is an important feature of the simple line graph?

-Is that one can immediately determine how the subject is performing at a glance. - Relatively nontechnical format for presenting the session-by-session data. -Is that it facilitates the evaluation of various characteristics of the data as they relate to visual inspection.

What is the advantage of bar graphs?

-Is that they present the results in one of the easiest formats to interpret. Day-to-day performance within a given phase is averaged, and that average (mean) is reflected in the height of the bar.

What is the goal in presenting data, and what does this mean in the case of graphing and visual inspection?

-Is to provide all the information feasible to allow the reader to make an evaluation. -Allowing the reader to apply the criteria or to see how the investigator applied the criteria.

What is represented by zero or no slope on a cumulative graph?

-Little or no change at all would be represented by a low slope or no slope.

What does the cumulative graph consist of?

-Nothing the level of performance of the subject over time in an additive fashion. The score the subject receives on one occasion is added to the value of the scores plotted on the previous occasions.

Plotting the means combines the advantages of ___ and ___ graphs.

-Simple line graphs -Bar graphs

What is represented on the x and y axis?

-The data are plotted so that the dependent measure is on the ordinate (y-axis). -The data are plotted over time, represented by the abscissa (x-axis).

What does each bar in a bar graph represent?

-The mean or average level or performance for a separate phase.

What is the easiest source of information to add to as simple line graph? What does this permit the reader to do and what does it provide?

-The plotting of means. -Plotting these means as horizontal lines or in an equivalent way for each phase readily permits the reader to compare the overall effects of the different conditions, that is, provides a summary statement.

What is the value of the score that is plotted on the cumulative graph?

-The value of the score that is plotted in the accumulated total for all previous days.

What is the major interest when conditions are changed?

-Whether the change level is beyond what would be expected from ordinary fluctuations in performance.