Definitions
A researcher wants to know the average commute time of all UTRGV students, so they survey 200 randomly selected students. In this case, the 200 students are called this, while all UTRGV students are called this.
Sample; Population
Survey participants list their favorite color.
nominal
What is included in the five number summary? How do you calculate all of the values?
Minimum, Q1, median, Q3, and maximum
Shows the data's spread/central tendency
What is the formula to find the population standard deviation?
σ = √(∑(x - μ)² / N)
Is attendance mandatory? After how many session are you emailed for being absent?
Yes!
2 sessions
A numerical summary of a population is called this, while a numerical summary of a sample is called this.
Parameter; Statistic
Temperature measured in Celsius is at this level of measurement.
Interval
This describes the shape of a distribution where most data fall to the left of the mean, with a “tail” extending rightward.
Positively skewed (right-skewed) distribution
What is the formula for sample variance?
s = √(∑(xᵢ- x̄)² / N-1)
Up to how many minutes are you allowed to be late before you are marked absent?
5 Minutes
These variables can take on an infinite number of values between any two values and are obtained by measuring (e.g., height, weight).
Continuous variables
A professor assigns letter grades (A, B, C, D, F) to students.
Ordinal
The quiz scores are 5, 7, 8, 10. What is the mean?
7.5
What type of distributions does the Empirical rule apply to? What are the percentages for Empirical rule
Empirical rule applies to normal distributions only. 68% of the data falls withini 1sd, 95% of the data falls with 2 sd, and 99.7% of the data falls within three standard deviations.
What should you do if you know you will miss PLTL
Email the professor your excuse and cc your PLTL leader!
Name the four levels of measurement for variables, starting from the lowest to the highest.
Nominal, Ordinal, Interval, Ratio
Blood pressure readings in mmHg are taken from patients.
Ratio
The exam scores are 60, 70, 80, 90, 100. If one more student scores 60, what happens to the mean and the mode?
New mean = (60 + 70 + 80 + 90 + 100 + 60) ÷ 6 = 76.7; Mode = 60
What type of distributions does Chebyshev's theorem apply to? What are the percentages that Chebyshev's theorem follows?
Chebyshev's theorem applies to all distributions. 75% of the data falls within 1sd, 89% of the data falls within 2sd.
What is your PLTL Leader's name and email?
Emilia
emilia.mendez01@utrgv.edu
This graph displays cumulative frequency for classes in a distribution.
Ogive
Highschoolers SAT Scores
Interval
For the data set 3, 5, 7, 8, 10, 12, 13, 15, 18, find the five-number summary.
Minimum = 3
Q1 = 7
Median = 10
Q3 = 13
Maximum = 18
The test scores are 4, 7, 9, 10. Find the sample standard deviation (round to two decimal places).
Mean = (4 + 7 + 9 + 10) ÷ 4 = 7.5
Deviations: (4 – 7.5) = –3.5, (7 – 7.5) = –0.5, (9 – 7.5) = 1.5, (10 – 7.5) = 2.5
Squared deviations: 12.25, 0.25, 2.25, 6.25 → Sum = 21
Variance (sample) = 21 ÷ (4 – 1) = 21 ÷ 3 = 7
Standard deviation = √7 ≈ 2.65
When is your PLTL Leader's office Hours
Friday 10AM-1PM
ELCTR 112