Types of Data
What type of data is the number of pets each student owns?
Discrete
What sampling method gives every member of a population an equal chance of being chosen?
Random sampling
What are the symbols for sample mean and population mean?
sample mean - x bar
population mean - mu
A data set has a standard deviation of 0. What does this mean?
All values are the same
What does a box and whisker plot show?
Min, Q1, Median, Q3, Max
What type of variable is height?
continuous
A survey sent by email only gets responses from tech-savvy people. What error is this?
Non-response error
Which measure of centre is most affected by an outlier?
Mean
Data value Frequency
2 2
3 3
4 7
5 5
Find the standard deviation
0.963
In a cumulative frequency graph, where do you find the median?
At the 50% mark on vertical axis
Discrete or continuous?
Time spent in a supermarket
continuous
What sampling method is used when selecting every 10th person?
Systematic Sampling
What measure of center uses all values in the dataset?
mean
Consider a data set with a standard deviation of 5.
Find the new standard deviation if each number is increased by 2.
5
What do parallel box plots help us compare?
Distribution of two or more datasets
What’s the difference between discrete and continuous data?
Discrete = counted, Continuous = measured
Why might convenience sampling lead to biased results?
It may not represent the whole population
A small school calculates the average salary of its teachers and includes the principal’s much higher salary. What measure should the school use to represent the typical teacher salary?
median
A teacher records test scores: 65, 67, 70, 72, 90.
An outlier is found. How will removing the outlier affect the mean and standard deviation?
Removing the outlier (90) will lower the mean and decrease the standard deviation, since 90 was pulling both higher.
How do you mathematically identify an outlier?
Q1-1.5 IQR
Q3+1.5 IQR
What kind of data is collected when recording the brand of car each person drives?
categorical
Describe how stratified sampling works.
Population divided into groups; random samples taken from each group
The mean mark is 4.6 . Find the value of k.
Mark Frequency
1 0
2 4
3 6
4 k
5 8
6 6
7 6
k=10
Consider a data set with a standard deviation of 5.
Find the new variance if each number is multiplied by a.
25a2
What percentage of data values are greater than Q1 ?
75?