Data recording, analysis and presentation Flashcards
What is raw data?
Raw data is the data that psychologists collect for each participant.
What is nominal level data?
Data that are produced as named categories. Closed questions often produce nominal data, as well as observations which code behaviour.
What is ordinal level data?
Data which can ranked in ‘order’. There needs to be an increase in value of points along your data , but the size of each increase does not need to be equal. The data is not continuous.
What is interval level data?
The divisions between the points on an interval scale are equal. For example, time, volume, speed, height, weight etc.
What is primary data?
When a researcher collects data either by witnessing an event or by carrying out an experiment or questionnaire. It can be quantitative or qualitative.
What is secondary data?
When data is collected second hand, which is through the analysis of pre-existing data, we call this secondary data.
What is mean and how is it calculated?
The average of the numbers. It is calculated by adding up all the scores and dividing by the total number of scores.
What are the strengths and weakness of the mean?
It uses all of the values in the data set, so is the most sensitive value.
When there are extreme values or outliers, the mean can be skewed.
What is the median and how is it calculated?
The middle number. It is calculated by finding the middle score after placing all the scores in numerical order.
What are the strengths and weakness of the median?
When there are extreme values the median is less affected than the mean.
It is less sensitive to variations in the data, so may not present a true picture.
What is mode and how is it calculated?
The value that appears most frequently in a set of data. When there is more than one number that appears the most frequently, we call this bimodal.
What are the strengths and weakness of mode?
When there is frequency/categorical data, as the others are not appropriate.
There may be no modal value or several.
What is range and how is it calculated?
The difference between the lowest and highest values. It is calculated by subtracting the lowest score from the highest score in a data set.
What are the strengths of calculating the range as a measure of dispersion?
Easy to calculate.
Takes into consideration extreme score
What are the weaknesses of calculating the range as a measure of dispersion?
Only using two scores in the data set and ignoring the rest.
The extreme scores could distort the range
What is variance and how can it be interpreted?
Tells us about the spread of scores around the mean. So a small variance would imply that the scores are all similar and close to the mean. A large variance would indicate that the scores are at a larger distance from the mean.
What are the strengths of calculating the variance as a measure of dispersion?
Is not very distorted by extreme scores.
The SD is closely related to the mean and is the best measure of dispersion to use when the mean is being used as the measure of central tendency
What are the strengths of calculating the variance as a measure of dispersion?
Is not very distorted by extreme scores.
The SD is closely related to the mean and is the best measure of dispersion to use when the mean is being used as the measure of central tendency
What are the weaknesses of calculating the variance as a measure of dispersion?
Takes a long period of time to calculate.
Assumes a normal distribution
What is standard deviation and how is it calculated?
The square root of the variance, so it tells us the average amount a number differs from the mean.
What are the strengths of calculating the SD as a measure of dispersion?
SD is the most sensitive measure of dispersion as it is derived by using every score in the data set and Is not very distorted by extreme scores.
The SD is closely related to the mean and is the best measure of dispersion to use when the mean is being used as the measure of central tendency .
What are the weaknesses of calculating the SD as a measure of dispersion?
Takes a long period of time to calculate Assumes a normal distribution.
What is a ratio?
A ratio is how much of one thing there is compared to another thing.
When are line graphs used?
These are used to show the results from two or more conditions at the same time.
Continuous data.
What axis does the IV and DV go on a line graph?
IV goes on the X axis
DV goes on the Y axis
What is a pie chart and what type of data is required?
Are used when we have percentages. Each segment represents a percentage of the total.
Nominal level data.
What are a bar chart and what data is required?
Bar charts can be used to represent the data from frequency tables, mean scores or the totals.
They are used with nominal or ordinal levels of measurement.
The bars are kept separate from each other.
What type of data is used in a histogram and how are they laid out?
Histograms are used with interval data. There are no gaps between the columns to represent a continuous data set.
How is frequency density calculated in a histogram?
frequency / class width
When are scatter graphs used?
Are used with correlations where the relationship of two variables is summarised.
Draw a normal distribution curve and what is the shape known as?
Bell curve
What is a level of significance?
This is the level at which psychologist will reject the null hypothesis, typically 95 per cent.
So there is a 95% probability of the independent varible having affected the dependent varible having affected the dependent varible and 5% likelihood of it being simply due to chance.
How is the level of significance shown?
p < 0.05
Where p = the probability of the results being due to chance
0.05 = 5%
What is type 1 error?
The alternative hypothesis is accepted and the null hypothesis is rejected, the behaviour being shown is down to chance.
What is type 1 error?
The alternative hypothesis is accepted and the null hypothesis is rejected, the behaviour being shown is down to chance.
What is type 2 error?
The rejection of the alternative hypothesis and the acceptance of the null hypothesis, when the IV is really having a significant impact on the DV.
What level data and experimental design is required for a Chi-Square test?
Independent measures
Nominal