data analysis : graphs Flashcards
what is the form of summary table used for ?
a way of representing data
what is the summary table not merely but instead ?
raw scores but have been converted to descriptive statistics
what is standard practice to include beneath the table ?
a summary paragraph explaining the results
define bar charts
a type of graph in which the frequency of
each variable is represented by the height of the bars
what can data be represented ?
visually using a suitable graphical display so the difference in mean values can be easily seen
when are bar charts used ?
when data is divided into categories
–> known as discrete data
what occupy the horizontal x-axis ?
the categories of the two conditions (typically CV)
what is plotted in the y-axis ?
the frequency or amount of each category (typically DV)
what are bars on a bar chart ?
separated on a bar chart to denote that we are dealing with separate
conditions
define scattergram
a type of graph that represents the
strength and direction of a relationship between
co-variables in a correlational analysis
what do scattergrams depict between covariables and not ?
they don’t depict differences but rather association
where do the covariables have to lie ?
either x-axis or y-axis it doesn’t matter where
what does each point on the graph correspond to ?
it corresponds to to the x position and y position of the co-variables
what must a table and graph always have ?
a title and clearly label columns or axes
what do the bars do in a histogram and why ?
touch each other
–> as it shows that data is continuous
what is the x-axis made up of ?
equal -sized intervals of a single category
what does the y-axis represent ?
the frequency within each intervals
what would happen if there was zero frequency for one of the intervals ?
the interval remains but without a bar
what type of data does line graphs represent ?
continuous data
how are points used in line graphs ?
they are connected by lines to show how something changes in value
what is plotted within the x-axis in a line graph ?
the IV
what is plotted within the y-axis in a line graph ?
the DV
define normal distribution
a symmetrical spread of frequency
data that forms a bell-shaped pattern. -the mean, median
and mode are all located at the highest peak
give an example of normal distribution in everyday life and what does that mean ?
the height of all the people in your
school/college
–> should form a bell-shaped curve
–> most people are located in the middle area of the curve
–> very few people at the extreme ends
the normal distribution is …
symmetrical
what does the ‘tails’ of the curve do ?
extend outwards and never touch the horizontal x-axis (never reaches 0)
why does the ‘tails’ of the curve do this ?
as more extreme scores are always theoretically possible
define skewed distribution
a spread of frequency data that is
not symmetrical, where the data clusters to one end
what do skewed distributions do ?
distributions that appear to lean to one side or the other
define positive skew
–a type of distribution in which the long tail is on the positive (right) side of the peak and most of the distribution is concentrated on the left
give an example of positive skew
a very difficult test in which most people got low marks with only a handful of students at the
higher end
–> this would produce a positive skew
what affects the normal distribution ?
the mean
what affects the normal distribution a lot less or not all ?
the mode and the median
give an example of negative skew
a very easy test would produce
a distribution where the bulk of the scores are concentrated on the right
–> resulting in a long tail of anomalous scores on the left
what order does the mean mode and median go in for negative skew ?
left to right
mean –> median –> mode
what order does the mean mode and median go in for positive skew ?
left to right
mode –> median –> mean
define negative skew
a type of distribution in which the long tail is on the negative (left) side of the peak and most of the
distribution is concentrated on the right
