Psy-B Paper 3 Analysing Data Key Terms

This set of vocabulary flashcards covers essential statistical terms for Psy-B Paper 3 Q2, including measures of central tendency, dispersal, distribution types, and correlation analysis.

Mean

The mathematical average of a set of data, calculated by summing all values and dividing by the total number of values.

Mode

The value that appears most frequently in a data set.

Median

The middle value in a data set when all scores are arranged in numerical order.

Measure of central tendency

A summary statistic that represents the center or typical value of a dataset, such as the mean, median, or mode.

Measure of dispersal (spread)

A statistic that describes how spread out or varied the data points are within a set.

Standard deviation

A measure of dispersal showing the average amount that each score deviates from the mean.

IQR

The Interquartile Range, which measures the spread of the middle $50\%$ of a data set.

Outliers

Extreme data points that lie significantly outside the range of the rest of the observations in a data set.

Skew

A measure of the asymmetry of a probability distribution around its mean.

Positive (right) skew

A distribution where most scores are clustered at the lower end, with the tail extending to the right side.

Negative (left) skew

A distribution where most scores are clustered at the higher end, with the tail extending to the left side.

Normal Distribution

A symmetrical, bell-shaped frequency distribution where the mean, median, and mode are all located at the same central point.

Descriptive Statistics

Numerical or graphical procedures used to summarize and describe the main features of a collected data set.

Inferential Statistics

Statistical techniques used to make generalizations or predictions about a population based on data from a sample.

Boxplot

A visual display of the distribution of data showing the minimum, maximum, median, and quartiles.

Correlation

A statistical measure of the extent to which two co-variables are related or associated with each other.

Positive Correlation

A relationship between two variables where as one variable increases, the other variable also increases.

Negative Correlation

A relationship between two variables where as one variable increases, the other variable decreases.

Strong Correlation

A relationship where the data points fall very close to a straight line of best fit, indicating a high degree of association.

Weak Correlation

A relationship where the data points are widely scattered, indicating a low degree of association between the variables.

if the mean is much lower than the median, this means that …

There is a left (negative) skew.

If the mean is much higher than the median this means that …

There is a right (positive) skew.

If the mean and the median are the same or similar this means that …

the data is normally distributed

If the median is at the right end of the box on a boxplot this means that …

there is a left (negative) skew in the middle 50% of the data

If the median is at the left end of the box on a boxplot this means that …

there is a right (positive) skew in the middle 50% of the data

if the standard deviation is large but the IQR is not, this means that …

there are probably outliers in the data

If the standard deviation is large but the mean and median are the same (or similar) this means that …

the data is widely spread but is also evenly spread (no skew, no outliers)