Blog

It seems reasonable to assume that ovulation rate and litter size in pigs would be positively correlated.  In other words, if a sow releases more eggs (i.e., ova) in a given estrus period, she will probably end up producing more pigs in her litter.  Number of eggs ovulated and litter size for a random sample of 6 sows are as follows: Number of Eggs, X       Number of Pigs Born, Y                14                                  7                15                                  7                16                                  9                17                                 10                17                                 10                17                                  11 Given that the variance of Y (number of pigs born) is 2.8 pigs2 (in the interest of time, I have calculated this value for you), find the correlation between X and Y.

A crop scientist would like to know the average yield of soybeans in Ohio (in bushels per acre).  A random sample of 225 soybean fields in Ohio yields a mean of 48 bushels per acre and a standard deviation of 7.5 bushels per acre. Estimate the population mean for the yield of soybeans In Ohio using a point estimate.

The value of a population parameter (e.g., the mean, μ) is a constant; its value does not change; in other words, it does not vary from sample to sample.

When we perform hypothesis testing, we specify a value for α (alpha), where α represents:

A __________ – tailed hypothesis test is one in which the alternative hypothesis is directional and includes the less than or greater than symbol.

The normal approximation to a binomial probability distrubtion is reasonably good even for small sample sizes (say, n as small as 10) when p = 0.5 and the distribution of X is therefore symmetric about its mean.

An ____________ is an object (animal, plant, person, or thing) on which we collect measurements.

We are interested in estimating the average driving time of students who commute to Ohio State.  From data sampled previously, we believe that the longest driving time is 66 minutes and the shortest driving time is 18 minutes.  How many students who commute need to be included in our sample to order to be 98% confident that the estimated mean driving time will be within 4 minutes of the true population mean driving time?

Suppose x has a binomial probability distribution with n = 150 and p = 0.60.  Use the normal approximation to the binomial to find P(X>100).

A local consumer reporter wants to compare the average costs of grocery items purchased at three different supermarkets – Kroger, Giant Eagle, and Meier.  Prices (in dollars) were recorded for a sample of 60 randomly selected grocery items at each of the three supermarkets.  In order to reduce item-to-item variation, the prices were recorded for each item on the same day at each supermarket. Item                          Kroger    Giant Eagle    Meier     1) Big Thirst Towel      $1.21       $1.49          $1.59 2) Post Golden Crisp    2.78         2.99            3.35 3) Tylenol Tablets         5.98         5.29            5.98           .                              .              .                   .           .                              .              .                   . 59) Colgate Shave       0.94         1.10            1.19 60) Kidney Beans        0.45          0.56            0.38                                                                                   The results of the Analysis of Variance for this experiment are as follows: Source           df       SS            MS          F     Total                       222.21     Supermarket              2.64       1.32       39.23 Item                        215.59       3.65     108.54 Error                           3.97      0.0337                                                                                What are the correct degrees of freedom for total, supermarket, item, and error, respectively?