Stats 1 Flashcards
What are the stages involved in creating a statistical model?
- A real life problem is observed.
- A mathematical model is devised.
- The model is used to make predictions.
- Experimental data is collected.
- Expected outcomes are obtained.
- Statistical tests are used to see how well the mathematical model works.
- The model is refined in light of comparisons with the data.
What does a box plot show?
The middle 50% of the data. It shows the upper and lower quartiles and the median. The whiskers represent the overall spread of the data outside the given range. The shape shows the skewness of data.
What is a statistical model?
A model to represent a more complicated real life problem. Models are often cheaper and easier to make. The model doesn’t represent the real problem in every detail so is a simplification of the real thing. They can be used to improve our understanding of the real world object.
How do you find the mean from a frequency table?
Divide the sum of frequency x point by the total frequency.
When are histogram so used to represent data?
They can be used for continuous data and frequency grouped data.
What is the underlying feature associated with each of the bars in a histogram?
The area of the histogram bar is proportional to the frequency of that class.
How do you find the equation of a regression line in form y=a+bx?
b= ((n x {sumof}xy) - ({sumof}x x {sumof}y)) % ((n x {sumof}x^2) - ({sumof}x)^2))
a= ({sumof}y % n) - (b)({sumof}x % n)How do you calculate the area of a bar in a histogram?
Frequency x a positive constant.
How do you calculate the height of a histogram bar?
Divide frequency with the class width.
What is a relative frequency histogram?
A histogram where the frequency is divided by the total frequency. This gives the total area as 1.00
How do you work out the median from tabular frequency data?
Interpolation: (lower class boundary of the median class)+(1/2n-sum of frequencies below median class / frequency of median class) x class width of median class
