research methods Flashcards
negative skew
the mean is on the left side of the median and mode so the tail is on the left.
this shows that a large amount of data falls above the mean score
positive skew
the mean is on the right side of the median and mode therefore the tail end is at the right side.
this shows that a large amount of data falls below the mean score.
skewed distributions
scores are clustered to one side of the mean.
distribution curves
(plot the frequency)
data can be distributed in different ways, either normal distributions or skewed distributions.
normal distribution
displays frequency data in a symmetrical bell shape pattern.
the mean ,median and mode are all located at the highest peak and the dispersion of scores around both sides of the average is consistent and expressed In standard deviation.
why do the tail end on normal distributions never touch the x axis
because extreme scores are always theoretically possible.
pie charts
used with discrete data.
each segment of circle represents a proportion of scores.
line graphs
also illustrate continuous data and use points connected by lines to show how something changes in value.
dv is plotted on y axis and iv plotted on x axis
histograms
illustrate the distribution /frequency of data items -continuous scores.
frequency on y axis and equal size intervals on x axis.
scattergram
used to show a relationship between two variables.
one co variable on x axis, one co variable on the y axis
a line of best fit may be drawn to estsblish the strength of relationship.
bar chart
used to make comparisons between scores and are used with different groups /categories of data (discrete data)
graphs
provide visual representation of a set of data that allows us to see the patterns in an east to understand way
tables
show a summary of the raw scoresconvverted to descriptive statistics.
small standard deviation
data points tend to be close to the mean pot the set
large standard deviation
data points are spread out over wider range of values
positive of standard deviation
sensitive and precise measure of dispersion as all values are take into consideration when calculating it.
negative of standard deviation
doesn’t tell you full range of the data and it can be affected by extreme scores to give a skewed picture
standard deviation defiition
statistical measure of variation in a set of data and describe how much, on average, all values differ from the mean.
range
the difference between the highest and lowest values
positive of range
easiest measure of dispersion to calculate
negative of range
only takes into account most extreme scores which makes it unrepresentative of the data set as a whole.
measures of dispersion
range - basic measure
standard deviation-sensitive measure
advantages of the mode
easiest measure to calculate and unnfacected by extreme values
its the only measure you could calculate when data is in categories eg nominal.
negative of mode
crude measure and can be unrepresentative in small data sets
becomes less useful when there are several modes in a data set