Descriptive statistics, graphs and ethics.

• Mean is the average of a set of data.
• Median is the central value in a set of data.
• Mode is the most common number in a set of data.
• The mode is unaffected by extreme scores and can be used with nominal data about frequency.
• The mode ignores values and only looks at frequency of values. But it can be unclear as there could be several.
• The median uses all the values and is not as biased and can be used with ordinal data.
• The median is more open to bias from extreme scores and can be unhelpful for further anaylsis.
• The mean is appropriate for further analysis such as standard deviation and is appropriate for all data types.
• The mean is unaffected by extreme scores and may produce a value that no participants received.
• Measures of dispersions
• Range is the difference between the highest and lowest value.
• The range is the simplest measure of dispersion. It is easy to calculate compared to standard deviation as you only subtract lowest value from highest value. It takes into account extreme values.
• Standard deviation is a measure of spread, an average measure of dispersion based on mean.
• Low standard deviation is when data is clustered around the mean.
• High standard deviation is data dispersed over a wider range of values.
• Standard deviation is used to understand if a specific data point is standard eexpected or unusual and unexpected.
• 68-95-99.768% fall within the 1st standard deviation within the mean.
• 95% falls within 2nd standard deviation within the mean.
• 99.7% fall within the 3rd standard deviation within the mean.
• Standard deviation tels us about the coonsistency of the data.
• Standard deviation gives a more precise measure of dispersion and reflects every score, therefore you can see how clustered the scores are around the mean. It is less affected by anomalous results.
• Standard deviation cannot be used with nominal data and cannot be used when data set is positively or negatively skewed.
• Work out the mean of the scores. Then minus each score from the mean.
• Square the scores then add all the squared numbers together.
• Divide the total by the amount of numbers minus 1
• Then square root the answer.
• Line graph ordinal interval ratio and continuous data, all the same rules for histograms, y axis = frequency starts at 0, x axis = continuous, dot a point and join.
• Pie chart nominal and discrete data, represent frequency data, slice represents a fraction of the total, calculate by working out proportion of 360 degrees, frequency/total x 360.
• Frequency table nominal
• Bar chart discrete data in categories, nominal data, can compare means from 2 different conditions, gaps between bars, y axis = frequency, x axis = categories.
• Histogram ordinal interval ratio continuous data, y axis = frequency start at 0, x axis = continuous 0-10 10-20, area in the bar is proportional to frequencies represented, no gaps between bars.
• Scatter graph uses correlations each axis represents a co-variable, a dot represents a participant, scatter of dots is the degree of correlation between co-variables.
• Normal distribution is a bell shaped curve for data that is evenly distributed, mean median and mode, inexact midpoint, distribution is symmetrical around midpoint, the y axis = frequency and x axis = item of interest, consistent and can be expressed at standard deviation.
• Positive skew distribution, majority to the right. Negative skew distribution majority to the left. Frequency distribution, y axis = frequency and x axis = item or interest. Used when scores are not evenly distribution around the mean when there are a number of extreme values to one side of the mid score.
• Parental consent is when ppts are too young to give consent so gain ti from their parents (under 16's).
• Prior informed consent - general consent form ppts of things that 'could' happen.
• Presumptive consent is consent from similar set of ppts who won't be doing the study.
• Valid consent is when ppts are asked to give permission to take part in a study and know the nature of the study.
• Deal with valid consent as ppts should be given a consent form detailing true nature and aims of study, children under 16 or vulnerable adults cannot give consent so need to obtain from a guardian.
• Deception is when ppts are not told the true aims of the study or are deliberately misled on one or more aspects of the study.