Download Top 10 Phrases to Memorize

AP Statistics
the top 10 phrases to use in your answers
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Bracketed words/phrases indicate that a choice of one of them is needed
Underlined words/phrases indicate that context is needed (substitute the actual
variable(s) from the problem)
Phrases 1 – 4 : linear regression

correlation between 2 quantitative variables ( r ):
“ There is a [ weak / moderate / strong ] [ positive / negative ] linear association
between explanatory variable and response variable.“

coefficient of determination ( r2 ):
“ x percent of the variation in response variable can be explained by the approximate
linear relationship with explanatory variable.“

slope of the LSRL ( b1=b in calculator ):
“ For every 1 unit increase in the explanatory variable, our model predicts an average
increase of y units in the response variable.“

y-intercept of the LSRL ( b0=a in calculator ):
“ At an explanatory variable value of 0 units, our model predicts a response variable value
of y units.“ (also comment on whether this value makes any sense)
Phrases 5 – 6 : confidence intervals

confidence interval:
“ I am confidence level% confident that the true population [ proportion / mean ] of
variable is between lower bound and upper bound.“
- or “ I am confidence level% confident that the interval ( lower bound , upper bound )
captures the true population [ proportion / mean ] of variable.“

confidence level:
“ If this [ poll / experiment ] were repeated many times, then about confidence level%
of the resulting confidence intervals would contain the true [ proportion / mean ] of
variable.“
Phrases 7 – 10 : hypothesis tests

stating the null hypothesis ( H0 ):
“Null hypothesis: The [ proportion / mean ] of variable1 is not different than the
hypothesized value (or the [ proportion / mean ] of variable2 ).“
The statement of the null hypothesis can differ depending on the problem but it
should indicate that there is no difference or no change (for example, with chi-squared
test of independence, the null hypothesis is that the two variables are independent or
not dependent); try to use the word NOT.

meaning of the p-value:
“This p-value of p-value% is the probability of getting a result as extreme or more
extreme than the one observed if the null hypothesis is correct.“

reject the null hypothesis:
“Since the p-value of p-value% is less than the significance level% level of significance,
there is convincing evidence that the null hypothesis should be rejected in favor of the
alternative hypothesis.“

fail to reject the null hypothesis:
“Since the p-value of p-value% is not less than the significance level% level of
significance, there is not convincing evidence that the null hypothesis should be rejected.“