ch 5/6 Flashcards
when shifting data, if the value of 10 is added to the observations, what happens to the mean/median?
it shifts by the same amount
when shifting data, do the measures of spread change?
no
when scaling data, what happens to mean/median
they get multiplied by the constant c
when scaling data, if an instructor gives students an additional 8% what becomes constant c
1.08
100% plus another 8%
when scaling data by 1.2, what happens to variance?
and SD?
variance: 1.2^2 x original variance
SD: 1.2 x original SD
what does z-score tell us?
how many SD the value is away from the mean
what does a negative z-score represent
the value is below the mean
the standard normal model has a mean of __ and a SD of __
0,1
what 3 normal model percentages have the rule
68, 95, 99.7
how many SD is 68% within the mean
1
problem: if the mean is 110, SD is 25, and we want to find the percentage of scores below 160, how do we do this
figure that the diff between the mean and 160 is 50, which is equal to 2 SD, meaning we can use the 95% rule. since 95% leaves 2.5% open on each side we do 95%+2.5% to get 97.5% as the answer.
what are scatterplots used for
determining relationship between 2 quantitative variables
for scatterplots the x axis should have the ___ variable, and the y axis should have the ___ variable
explanatory, response
what does correlation refer to?
the degree of linear association between 2 quantitative variables
what does “r” stand for
correlation
