Research Methods - Data Handling and Analysis Flashcards
What are tables?
Raw scores displayed in columns and rows. A summary paragraph beneath the table explains the results.
What are bar charts?
- Used for presenting nominal data (in the form of categories). Categories (discrete data, the independent variable) are usually placed along the x axis, with the frequency (or dependent variable) on the y axis. This can be reversed.
- The height of each column represents the frequency.
- Compound bar charts tend to be difficult to interpret.
What are histograms?
- Bars are touching each other.
- Data is continuous rather than discrete.
- There is a true zero.
- It is used when data falls on a continuous scale (ordinal or interval).
- Frequency is plotted on the y axis.
- Dependent variable is on the x axis.
- Any gaps suggest that there was no data in that class.
- The width of a histogram shows the range of results.
- The shape can also indicate the trend in data.
What are line graphs/frequency polygons?
- Frequency on one axis, data on the other axis is continuous.
- The line often shows how something changes, e.g. over time.
- Can be used in similar ways to the histogram (ordinal and interval data).
- Useful for displaying two or more sets of data (e.g. individual results in two conditions).
- Useful to display trend.
What are scattergrams?
- Used for correlational analysis. Each dot represents one pair of related data.
- The data on both axes must be continuous.
What is a normal distribution?
- Symmetrical, bell-shaped curve. Most people are in the middle area of the curve with very few at the extreme ends.
- The mean, medium and mode all occupy the same mid-point of the curve.
What is a skewed distribution?
Distributions that lean to one side or the other because most people are either at the lower or upper end of the distribution.
What is a negative skew?
Most of the distribution is concentrated towards the right of the graph, resulting in a low tail on the left.
The mode is the highest point of the peak, the median comes next to the left, and the mean is dragged across to the left.
What is a positive skew?
Most of the distribution is concentrated towards the left of the graph, resulting in a long tail on the right.
The mode is the highest point of the peak, the median comes next to the right, and the mean is dragged across to the right.
What are the levels of measurement?
- When carrying out research, psychologists collect data.
- Sometimes the data is qualitative, but many of the techniques produce quantitative data.
- The information collected varies in how precise it is.
- The “levels of measurement” refers to these differences in precision.
- It’s important to assess the level of measurement.
What are the three types of data, from the most basic to the most precise?
- nominal
- ordinal
- interval
What is nominal data?
- This is the most level of measurement,
- Used when data is put into tally charts/categories. For this reason, it is sometimes referred to as category data.
- Gives very little information as it is basically a headcount, it only tells us how many people are in each group.
- Each item can only appear in one category. There is no order.
What is ordinal data?
- This is used when data can be put into order, e.g. 1st, 2nd and 3rd.
- If there is a scale, it’s ordinal data.
- It cannot tell us what gap is between 1st and 2nd, or between 4th and 5th (intervals are variable).
- Intervals are subjective.
- Usually based on opinion therefore tend to be subjective rather than objective, and so lacks precision.
What is interval data?
- The most precise level of measurement.
- Interval data is based on numerical scales that include units of equal, precisely defined size.
- e.g. the gap between 1 and 3 seconds is exactly double the gap between 1 and 2 seconds.
- e.g. the gap between 2 and 3cm is exactly the same as the gap between 10 and 11cm.
- Public units of measurement.
- Interval data is ‘better’ than ordinal data because more detail is preserved as the scores are not converted to ranks.
What are the measures of central tendency?
- mean
- median
- mode
What are the measures of dispersion?
- range
- standard deviation
What measure of central tendency would you use for each level of measurement used?
interval - mean
ordinal - median
nominal - mode
What is the mean?
The arithmetic average, add up all the scores and divide by the number of scores.