Statistics Flashcards
Mean
The sum of the items divided by the number of items.
How to calculate the mean for a frequency distribution?
1- Multiply each data value by its frequency
2- Find the sum of those products
3- Divide that answer by the total frequency of the distribution
Median
The data item in the exact middle number.
Or the mean of the two middlemost items.
Mode
The value that occurs most Frequently in a data set.
If more than one data value has the highest frequency then each of these data values is a mode.
Midrange
Lowest data value plus the highest data value divided by two
Range
Highest data value minus the lowest data value
Frequency distribution
Table with two columns
column one has data values
Column two has the frequency that data occurs
Inferential statistics
Making generalizations about drawing conclusions from data
Descriptive statistics
Concerned with collecting, organizing, summarizing, and presenting data
Measures of disbursement
Used to describe the spread of data items in a data set
Percentiles
Example: if I score is in the 45th percentile this means that 45% of the scores were less than that score
Z-score
Describes how many standard deviation’s a particular data item lives above or below the mean. The formula to find the Z score equals the data item minus the mean divided by standard deviation.
Normal distribution
AKA Gaussian distribution
On a graph it would appear to be a bell curve. The mean, median and mode are all equal and located at the center.
Standard deviation
Found by determining how much each data item differs from the mean.
A complicated formula involving square root.
Random sample
A sample obtained in such a way that every element in the population has an equal chance of being selected for the sample
