Introduction to statistics Flashcards
What is statistics?
Exploring. Analysing. Summarising data. Designing methods. Collect data. Drawing conclusions from data. Making decisions.
Where will we use statistic?
At university: Research. Communication. Design. Analysis of laboratory experiments. Surveys.
Career: Evaluating experimental results. Epidemiology. Pharmaceutical. Food industry. Clinical trials. Marketing studies. Sales. Data informing policies.
From where can the data come?
Laboratory experiments.
Questionnaires.
Observations.
What is a variable?
A characteristic of interest. Measured/observed. A factor for group data. Height. Cholesterol levels. Colour.
What can data be?
Numerical= measurements. Categorical = group.
Is the variables numerical or categorical? Height of males. Cakes produced. Gender. Voting. Education. Cholesterol levels. Salt concentration.
N. N. C. C. C. N. N.
When is a variable continuous or discrete?
When the variable is a measurement then it is continuous.
Is the variable discrete or continuous?
Weight. Participants. Height. Blood cholesterol concentration. Cell count. Enzyme activity. Live births. Reaction time (msecs).
C. D. C. C. D. C. D. C.
When is a variable nominal and when ordinal?
When the data can be ordered then they are ordinal.
Is the variable ordinal or nominal?
Gender. Army rank. Favourite restaurant. Voting. Education levels. Marital status. Exam grade. Council tax band.
N. O. N. N. O. N. O. O.
What do statistics summarise?
Centre.
Position.
Spread.
Shape of data.
Which are the measures that characterise the centre of a dataset?
Mean.
Mode.
Median.
What is the mode?
The most frequently occurring value in the data set.
What is a odal class in a histogram?
The most frequently occurring value range.
How many modal classes can we have in a histogram?
2 the most.
How can we calculate the mean?
Sum of all values/number of values (n).
How can we calculate the median?
When we put values in an order.
Find the number in the middle.
Formally: n + 1 /2 = value in dataset.
Find that value in that position we calculated.
Where can we find the mode?
In all types of variables.
Where can we find the median?
Only for ordinal or numerical variables.
Where can we find the mean?
Only for numerical variables.
How can we find the mode from an age group dataset?
Find the variable with the highest number of students.
= occur more.
How can we find the mode of a gender dataset?
Value with highest frequency = occur more.
Which are the measures of Position?
Quartiles.
Q1: lower quartile.
Q2: median.
Q3: upper quartile.
What do quartiles do?
Divide an ordered tests into specific/equal parts?
Characterise the shape of dataset.