equations
In the equation statistic +/- Z*(SE). What is the margin of error?
Z*(SE)
On average, how much do lawyers earn annually?
CI for mean
How many degrees of freedom will you use if n=50
N-1=49
Phat +/- Z* the square root of (phat(1-phat)/n)
Z* = 1.960
Z= (x-Mu)/ standard deviation
What is the CI equation for a paired mean.
XbarD+/- t*(standard deviation of difference /number difference
Do lawyers earn on average more than $100,000?
What is the Z score of a value of 3.7. When mu =4 and the standard deviation is 0.6.
-0.5
Sample proportion b = 0.52
What is our sample statistic phatA-pHatB=
0.24
What is the Central limit theorem for both means and proportions?
Proportions: np>10 n(1-p)>10
Means: sample sizes are >30
N= (Z*/ME)^2 p(1-p)
Is there evidence that there is a higher percentage of female students than male students who are in favor of making UWL a non smoking zone
Two sample test for difference in proportions
What is the SE equation for difference in means?
SE= The square root of (s1^2/n1 + s2^2/n2)
What is the SE for a difference in proportions?
The square root of p1(1-p1)/n1 + p2(1-p2)/n2
What are two ways to increase the width of a confidence interval?
1. Increase sample size
2. Increase Confidence level
How do you calculate the t statistic for a paired difference in means
T = (XBarD) / Sd/the square root of nd
D= difference
Do lawyers earn more on average than accountants?
Hypothesis test for Difference of means
What is the sample statistic for a paired difference in means test?
XbarDifference
If a confidence interval is (-.932, 2.127) Will you reject or fail to reject for a difference in proportions test
Fail to reject. 0 in interval
How do you convert z back to x?
X= Mu+ Z(standard deviation)
If the absolute value of a test statistic is greater than 2.5 then we can assume the P-value is statistically significant. If we have a test statistic = -2.7 is the P-value high or low.
Low- statistically significant.
Using only one group of men, estimate how much more or less they spend for food for the month of July than for the month of December
CI for the mean of paired differences
Interpret a CI for the following scenario : A sample of 12th grade females was surveyed about their seatbelt usage. A 95% confidence interval for the proportion of all 12th grade females who always wear their seatbelt was computed to be [0.612, 0.668].
The correct interpretation of this confidence interval is that we are 95% confident that the proportion of all 12th grade females who always wear their seatbelt in the population is between 0.612 and 0.668
Identify the 99, 95, and 90% CI out of the three:
(.317, 0.629)
(0.418, 0.582)
(0.401, 0.598)
99%
90%
95%
If you have a confidence interval for paired mean differences. How can you tell if you have statistically significant results?
0 would not be in the CI. 0 would indicate no difference