Intro to Stats Final Exam

• Categorical is a yes or no question, or has a non-numerical answer.
• A mode is the most common number in a set of data.
• Which statement best describes the shape of this histogram?

  The histogram is negatively left skewed.

  
• What statement best describes the shape of this histogram?

  The histogram is positively right skewed.

  
• If a relationship between a person's age (x) and the amount of retirement money they possessed (y) was found to have r^2=0.25, what can be concluded?


  25% of the variation in people's retirement income is explained by the linear relationship with age.
• The coefficient of determination is the square of the linear correlation coefficient.
• When the mean of a distribution is larger than the median, what is the shape of the distribution?

  Skewed to the right
• When the mean of a distribution is smaller than the median, what is the shape of the distribution?

  Skewed to the left.
• When the graph of a data is skewed to the right, what kind of measurement is the most representative?

  Median
• What form of statistics measurement is unaffected by outliers?

  Interquartile Range
• What could indicate that a data set is not symmetric or bellshaped?

  The mean is much smaller than the median.
• What is the effect of an outlier on a correlation value?

  The outlier will always change a correlation value so that it is closer to 0.
• What is a regression line used for?

  To estimate the change in y for a one-unit change in x.
• When Z is negative, it means what?

  The number of standard deviations of an observation is to the left of the mean.
• What is the area to the left of the mean for a standard normal probability distribution?

  0.5
• What is a characteristic of the normal probability distribution?

  The distribution is symmetric about the mean.
• What is the mean of a standard normal probability distribution always equal to?

  Zero.
• What is the standard deviation of a standard normal distribution always equal to?

  One.
• What is the formula for the standard error of the sample mean?

  Standard Deviation divided by the square root of N.
• When sample size increases, the standard error of the sample mean will decrease.
• What is the formula for standard error of a sample proportion?

  Square root of P(1-P) divided by N.
• A probability under 0.05% for a normal probability distribution is unusual.
• The margin of error on this photo is represented by what?

  C

  
• To check normality for a numerical problem with a confidence interval, check that n>30 or the npp of the sample is a straight line.