WEEK 2 Flashcards
(20 cards)
What is descriptive statistics
A way to summarise and describe key features of a data set
It describes features of the data rather than making inferences about the population
How is data described for numerical variables
Measures of central tendencies (mean, median and mode) and measures of variability (IQR, standard deviation, variance and range)
Another word for mean
Average
What is the median
the middle number in a sorted list of numbers (if it’s even, plus the 2 middle numbers and divide by 2)
What is the mode
The most common number (can have multiple modes)
What is the IQR
The range of values that resides in the middle of the scores. It shows the skewness of a dataset
What is the standard deviation
It tells you, on average, how far each value lies from the mean.
In other words, it is the average amount of variability in your dataset
How is data described for categorical values
Observations made from qualitative data (data that is typically non-numerical)
Frequency tables, percentages, visualisations (such as pie charts, two-way tables or bar charts), mode and measures of spread (for ordinal data)
Which side is the tail located on a negatively skewed graph
towards the left
In relation to the median on a negatively skewed graph, which side is the mean and the mode on?
The mean is towards the left side of the median and the mode is towards the right side
Which side is the tail located on a positively skewed graph
towards the right side
In relation to the median on a positively skewed graph, which side is the mean and the mode on?
The mean is on the right side of the median and the mode is on the left side
What are outliers and how can they be caused
A data point that differs significantly from other observations
An outlier may be due to variability in the measurement, an indication of novel data (data sources that are new, or typically not used for research), or may be the result of experimental error
Measures of centre
Median, mode and mean
Measures of spread (or variability)
IQR, standard deviation, range, variance
What is an independent variable
The variable you change or control. It’s the cause.
What is a dependent variable
The variable you measure or observe. It’s the effect.
In the following statement, what are the independent and the dependent variables?
The longer a student studies for an exam, the better their grades will be
Independent variable: time spent studying
Dependent variable: exam grades
In the following statement, what are the independent and the dependent variables?
The habitat of a bee depends on its species
Independent variable: species of the bee
Dependent variable: habitat
What does the correlation coefficient ‘r’ represent?
The strength and direction of a linear relationship between two variables. The value range of r is always between -1 and 1 and only works for linear relationships
If:
r = 1 it’s a perfect positive correlation (as one increases, so does the other)
r = -1 it’s a perfect negative correlation (as one decreases so does the other)
r = 0 it has no linear correlation
