Introduction to Statistics Flashcards
What are statistics?
Statisstics a collection of methods for collecting, displaying, analysing, and drawing
conclusions from data.
What are descriptive statistics?
Descriptive statistics is the branch of statistics that involves organising,displaying,
and describing data
What are inferential statistics?
Inferential statisticsis the branch of statistics that involves drawing conclusions about
a population based on information contained in a sample taken from that population.
What is Qualitative data?
Based on measurements for which there is no natural numerical scale, but which
consist of attributes, labels, or other non-numerical characteristics(observations).
Example: Most people appear to accept chiropractic as a safe treatment practice.
What is quantitative data?
Based on numerical measurements that arise from a natural numerical scale
Example: 90% of people accept chiropractic as a safe treatment practice.
What is absolute frequency?
The absolute frequency ( f ) is defined as the number of times the observation occurred in
an experiment or study.
Example: A patient has visited the clinic every Monday and Wednesday for 6 weeks.
What is their absolute frequency of visits per week?
f = 2 visits per week
What is the cumulative frequency?
The cumulative frequency ( f ) is defined as the sum of all previous frequencies within an
observation.
Example: A patient has visited the clinic every Monday and Wednesday for 6 weeks.
What is the cumulative frequency of visits far?
f = 2 per week × 6 weeks
f = 12 visits
What is a frequency distribution table?
A frequency distribution table can be used to display the frequency of various outcomes.
Example: A patient has visited the clinic every Monday and Wednesday for 6 weeks.
Illustrate this using a frequency distribution table.
or
Week# Week 1 Week 2 Week 3 Week 4 Week 5 Week 6
f 2 2 2 2 2 2
Day Mon Tues Wed Thurs Fri Sat Sun
f 6 0 6 0 0 0
What is a frequency histogram?
A frequency histogram can also be used to display the frequency of various outcomes.
Example: What day is the busiest for patients visit the chiropractic clinic?
This looks like a bar graph
What is the sample mean?
The sample mean (Xഥ) of a set of sample data values is defined as
the sum of all data values (∑X) divided by the number of data values (n).
Xഥ = ∑X ÷ n
Example: A random sample of 8 patients are selected with the following ages:
23, 24, 27, 28, 34, 38, 39, 55. Calculate the sample mean.
Xഥ = 268 ÷ 8
Xഥ = 34 years of age
What is the sample median?
The sample median represents the middle data value when data is arranged in numerical
order.
➢ For sample data for which there are an odd number of measurements, the median
represents the middle data value, when the data are arranged in numerical order.
➢ For sample data for which there are an even number of measurements, the median is
the mean of the two middle data values,when the data are arranged in numerical
order
What is the sample mode?
The sample mode of a set of sample data is the most frequently occurring value.
Example: Students were asked how much money they would like to spend on their
chiropractic consultation. This data is displayed in the frequency histogram below
What is the sample range?
The range (R) of a data set is difference between its largest (Xmax) and smallest (Xmin)
values
R = Xmax ─ Xmin
➢ A smaller range indicates less variability (less dispersion) among data.
➢ A larger range indicates more variability (more dispersion) among data.
What is Sample Standard Deviation (SD)?
The sample standard deviation (SD) of a set of sample data is calculated using the
following formula.
Step 1. Calculate the sample mean: Xഥ
Step 2. Calculate the deviation from mean for each value and square the result:[(X─ Xഥ )²]
Step 3. Calculate the sum of all squared deviations: ∑ [(X─ Xഥ )²]
Step 4. Divide this value by the sample size and minus 1: (n ─ 1)
Step 5. Square root this value to calculate the SD.
What is column/bar chart?
A column/bar chart shows the accumulation of data with cuboid bars (vertical or
horizonal) with different dimensions and lengths which are directly proportionate to the
values they represent.
