Data Analysis Flashcards
What is frequency distribution
A frequency distribution is a table or graph that presents the categories or numerical values along with their associated frequencies.
What is relative frequency
The relative frequency of a category or a numerical value is the associated frequency divided by the total number of data
Each part of a circle graph is called a
sector. And
since the area of each sector is proportional to the percent of the whole that the sector represents, the measure of the central angle of a sector is proportional to the percent of 360 degrees that the sector represents.
Estimate slope of a trend line?
Same as coordinate geometry - take any two points - y2-y1/x2-x1
dont forget to use unit - y axis. and this is for per unit of X axis. If x axis is in 10 units, multiply by 10
Weighted mean?
number of times every number is appearing in the set - n1xX + n2xY+ n3xZ+………./n1+n2+n2….
How to find diff quartiles?
Q2 = Median, follow normal formula - Average of N/2 and N+1/2
Q1 = Median of first two quartile groups
Q3 = Median of last two quartile groups
Range?
largest number minus smallest number
Interquartile range of numbers?
Q3-Q1
How many standard deviations is a given number away from a mean?
Take SD
Mean minus Number
divided by SD
That many SDs
in a scatter diagram, if the dots are closer to the trend line/regression line then what does it indicate?
it indicates “stronger” correlation. Could be positive correlation (line right to left increasing slope) or negative correlation (line right to left decreasing slope) and both can reflect strong correlation. Scattered points not tending towards trend line signify less to correlation
In a set if numbers are evenly spaced then what is mean of set equal to (n=odd)
median
standard deviation and mean formula
if there is a mean, standard deviation is the average distance the data values are away from the mean
normal distribution- what are %s of mean +/- d, m +/- 2d and m +/- 3d?
34%, 13.5% (95%), 2.5% (99%)
