Test 1 Flashcards
- Making sense of numbers - Samples - Variables
Do the numbers make sense?
- 300 jobs were created.
- Your salary increased by 2% increase this year.
Not telling the whole truth.
Make sure to question the data!
- BUT, 500 people were fired
- BUT, the cost of living increased by 4%.
What is cherry-picking?
Give an example.
Cherry picking is selecting only parts of the data that support a certain opinion.
A hockey team plays 25 games a season.
They lost 12 games, Tied twice, lost another two, won 7,Then lost 2
The parents get angry that the team has lost most games
The coach answered said that they have won 7 of the ten last games.
Who collects the data?
McDonald’s made a study saying that by eating their food everyday you will help you lose weight.
Be wary of who is collecting the data since they could have some sort of bias
For example: pharmaceutical compagnies doing their own research on their products.
Be wary of comparison.
EX: In July, ice cream sales increase - so do the numbers of drowning. In February, the both go down
Two things that happen at the same time doesn’t mean they are related
Are the numbers consistent?
In a sample of 20 Vanier students. 57% are in social science, 27% in science and 16% in technology
NO. They need to be intervals of five in this situation to make sense of the numbers.
Are the numbers consistent?
- One of my colleagues is complaining that 20% of his classes of their classes or on a Friday.
- 30% of crimes happen on the weekend (Saturday and Sunday)
The numbers are exactly what we think the are.
- Every school day has a 20% of classes (100% / 5days= 20%)
- (100% / 7 days = 14.28 14.28 x 2 = 30 )
Are the numbers possible?
The average student spends 8000 hours on instagram a year.
- NO, average of hours in a year 8760- that would mean that students don’t sleep and don’t go to school
Is the arithmetic right?
25% of men, 37% of women favour a 4-day work week, so 62% of people what this.
NO, Common errors is when adding percentages of different groups.
- Doesn’t equal to a100%.
Are these bad calculations?
- In Canada, 64% of those over 65 years are women and only 18% are men.
- At Vanier, 54% of the students are in social students, 35% are in science, 14% in commerce, and 36% are other programs.
- YES, Doesn’t equal to 100%, but 82%
- YES, Doesn’t equal to 100%, but 139%
What is a population?
Give an example.
A Population is all members of a group.
- All the people living in Québec
- All the students in Vanier college
- All canadiens over 18
What is a sample?
A sample is a part of a population at interest.
* A sample is selected form a population.
- one thousand canadiens over 18
- ten school in the province of Alberta
What is systematic sampling?
Go throught the whole population and systematically selected them.
EX: every fifth person makes is part of the sample.
What is a cluster sample?
A subgroup of the whole population.
EX: all the Asian restaurants in the population of all restaurants.
What is a stratified sample?
a specific type of a group within population. Could also be Proportional stratified sample if you know the amount of each group (representative of the population).
EX: 2 italian, 5 asian, 6 fast foods…
What is convenience sampling?
Choosing the members of a population that are easiest to reach.
EX: The students from your class from the whole Vanier population
What is voluntary sampling?
The members of your sampling are members who volunteered
What is a sample that is representative of a population?
The characteristics of the population are represented in the sample.
What is a sample that is biased of a population?
a sample that is biased means that the characteristics are either over of under represented.
What is Simple Random Sampling (SRS)? (explain the process)
SRS gives and equal chance to all the members of population to be selected from the sample.
1) Give everyone a number (0-???)
2) Get a computer to generate a series of numbers to randomly select a number.
What is a number that describes the population?
a Parameters
What is a number that describes a sample?
a Statistic
What can a parameter or a statistics be?
Proportion (fraction, decimal or percentage) or a mean (average)
What are the Quantitave methods symboles for sample size, sample proportion, sample mean, Population proportion, Population mean)
check screen shot of table.
What is an under-coverage sampling error?
When a group of a population is left out. EX: call people from a phone book for your sample, people with no phone or house is left out
What is a convenience sampling error?
It excludes people who aren’t convenient to you
What is a voluntary sampling error?
Certain kinds of people are more likely to participate in a study.
What is a random sampling error?
Even if you try to be as unbiased as possible your sample could still be baised..
What is a leading question non-sampling error?
Theses are questions that are ambiguous or that lead to a specific question. EX ; “Free music steaming is like stealing. You wouldn’t be oppose to a fee to stream music.
What is a error response non-sampling error?
The respondent make a mistake or gives and unclear answer. EX: How much music do you listen to? A little, a lot, 5 hrs…
What is a non-response non-sampling error?
Respondent don’t answer to question.
What is a processing error non-sampling error?
entering data and making a mistake EX: entering 100 instead of 10
What is a variable?
A variable is anything that can be measured
EX: age, gender, height, weather…
What is a attribute?
An attribute is a characteristic of a variable.
EX: what is your marital status?
MARRIED, SINGLE, WIDOWED..
What is the difference between a dependent and independent variable?
-Independent causes the change.
-Dependant is influence by the change.
What are the three levels of measurement and what does they measure?
- Nominal, attributes that cannot be ranked EX: dog cat fish…
- Ordinal, can be ordered EX: cold, cool, warm and hot
- Interval ratio, can be ranked and determine the difference between variables. EX; 100cm, 130cm, 150cm…
Why is it important to present data?
It is important to present data visually to easily understand it and organise the data.
Example of a frequency table? relative frequency table?
- Summarise the distribution of the data
- How each category compares to the total.
Example of a bar graph?
Shows the frequency of each attribute as a bar (don’t touch)
Example of pie chart?
Is a circle divided into segments, each segment is proportionate to the attribute
Example of Histograms?
continuous quantitative data. (The bars touch).
What do these words to describe a histogram mean?
- Symmetrical
-Skewed
- Positively Skewed
- Negatively Skewed
- outliner
- The distribution on the graph is roughly a mirror image
- it is not a mirror image
- The bump is at the beginning
- The bump is at the end
- There’s a little bump separated from the rest of the data.
