statistics Flashcards
what does the mean stand for and the symbol it uses
its the average of all values together then divided by how many values there
the symbol is the x bar line on top or fancy M
what does median stand for
middle values (arranged least to greatest then middle values) - if no middle and even amount number take average of middle values
what does the mode stand for
its the value that occurs the most often
what does the range stand for
the difference between largest / smallest values (sub largest from smallest)
what does standard deviation stand for
how much each value ges up/down from the mean and spread of data
- low # of sd shows more consistant
- high # sd shows less consistant
how to calculate mean / standard deviation when no frequency
-stat then 1
-edit and put values into L1
-then stat move over to calc
-then press 1 and enter
how to calculate mean / standard deviation when theres a frequency value
-stat then 1
-edit and put values into L1 and L2
-then press 2nd mode and calc
-push 1 and 2nd 1 then , 2nd 2
-enter
when finding the mode / sd what do you do if info just gives - in between 2 numbers
you have to take the average of them first
how to check something has normal distribution
-see if mean / median close
-when using the x graph method see if resembles curve
- see if data should be similer to what would be in one standard deviation
all values of data above the mean have what type of z score
positive
all values of data belloe the mean have what type of z score
negative
higher sd stand for what type of consistancy
lower consistancy because more high so means each time is farther away from mean less consis
lower stand deviation for what type of consistancy
it stands for being more consistant and is closser mean so more consistant
when do you use to calculate the z-score
formula) when you have 3 values you can re-arrange and solve for z score then use it to find percent ect
z= x - M / sd
when things go into the z-score what similarities do they MUST have
they must all be the same units
ex) all number of bottles or all comparing ml
how to find percent when given a z-score
- determine if its a neg bellow or above the mean
- go to chart for either pos or neg then the side up and down is the first values of z score the side to side is the last value z score
- then times by 100
(when looking for % and values are the same dstance apart then get average)
how to find z score from percent
- see if neg or pos go to that chart
- look for the % then times by 100 then look and the up and down values that make it first values then side to side values that make up last values
when asking for % to the left given z-score
1) if not given z score and trying to look for % first use formula to find z-score
2) after having z-score then look on chart to find the %
what to do when asking for % thats in-between 2 values
1) find z score from formula or if given
2) then use z-chart to find % for both z scores
3) then subtract the %’s to get middle value
what to do when asking for the % to the right
1) find z-score if not given by formula
2) then find %
3) subtract 100 from percent given
whenever question asking how many of other unit when having a percent how do you find how much
then turn % to dec divide by 100 times by other value
when looking for a data values percent and its on the graph already and isnt in-between any lines ect how do you find %
you would go off referance formula sheet and add up the % in the colums that would be shaded
when the confidence level increases what happens to the margin of error
the margin of error increases bc confidence level increases bc large margin of error is bigger range and easier to be confident with bigger range
when someone wants to be more confident in the results what must they do to increase it
take more samples because within more people you can be more sure that its the correct information
