# Statistics: Arithmetic Mean and Relative Frequency

1077 Words Sep 7th, 2013 5 Pages
HONORS STATISTICS

CH1

In an observational study, researchers simply observe characteristics and take measurements, as in a sample survey.

In a designed experiment, researchers impose treatments and controls and then observe characteristics and take measurements.

Data from a sample of citizens of a certain country yielded the following estimates of average TV viewing time per month for all the citizens.
Answer: Inferential, because the statistics are used to make inference about the population.

* 50 kids are divided into 2 groups. One is exposed to a vid on bullying. The other isn’t. After one week, both groups are questioned about their attitudes about violence. This is a designed experiment

5 state officials:
No, since the data is qualitative

4. Paved | 92 | 106 | 86 | 91 | 106 | 88 | 74 | DIRT | 69 | 58 | 50 | 57 | 60 | 93 | 109 |

Range of paved is .. 106 – 74 = 32 --- highest – lowest
Range of dirt is 109 – 50 = 59
Standard Deviation: Paved: A) All the values added together = x, then that value squared = x^2 B) Each value squared and then added together (92^2 + 106^2 + …)

Finding the answer: Square root of B – (A/number of values or N) N-1
Do the same for Dirt with other numbers

5. 10 numbers given 67 148 153 77 127 91 66 146 100 97 rearrange data in ascending order 66 67 77 91 97 100 127 146 148 153 a) obain quartiles:
Q2 = median --- 97+ 100/ 2 = 98.5
For Q1, Q3, split the data in to two parts
66 67 77 91 97 100 127 146 148 153 the median of the lesser data is Q1 and the median of the greater data is Q3

b) quartiles suggest the 25% of samples are less than Q1, 25% between Q1 and Q2, 25% between Q2 and Q3, and 25% greater than Q3

c) IQR = Q3- Q1
*number of units contained in the middle 50% of the samples span roughly (IQR answer) units

D) % number summary
Minimum, Q1, Q2, Q3, Maximum *The middle 50% has the greatest