7.18 Intrusion detection systems. The Journal of Research of the National Institute of Standards and Technology (November- December 2003) published a study of a computer intrusion detection system (IDS). The IDS is designed to provide an alarm whenever unauthorized access (e.g., an intrusion) to a computer system occurs. The probability of the system giving a false alarm (i.e., providing a warning when no in- trusion occurs) is defined by the symbol a, while the prob- ability of a missed detection (i.e., no warning given when an intrusion occurs) is defined by the symbol ß. These symbols are used to represent Type I and Type II error rates, respec- tively, in a hypothesis-testing scenario. a. What is the null hypothesis, Ho? b. What is the alternative hypothesis, Ha? c. According to actual data collected by the Massachusetts Institute of Technology Lincoln Laboratory, only 1 in 1,000 computer sessions with no intrusions resulted in a false alarm. For the same system, the laboratory found that only 500 of 1,000 intrusions were actually detected. Use this information to estimate the values of a and B.

Selecting the Appropriate Inferential Test: For each of the studies below, please identify the following (or indicate N/A "not applicable" if the feature is not relevant to the design): a) Independent Variable(s) (IVs) and # of levels for any IVs (for Correlation/Regression, identify the predictor and predicted variable rather than IV and DV) b) Dependent Variable (DV) c) Scale of Measurement for the Dependent Variable: (Nominal, Ordinal, Interval, Ratio) for Correlation/Regression please make sure you identify the scale of measurement for both variables d) Appropriate Statistical Test (If it is a Factorial ANOVA, make sure to name the design: e.g., 2 X 2, 2 X 3, etc.)

4) Consider the following table of data that shows the results of asking a group of people about yearly income: $20,000 – 29,999 $30,000 - 39,999 $40,000 - 49,999 Totals Male 49 80 127 256 Female 47 97 93 237 Totals 96 177 220 493 i) Determine the probability that one randomly selected person from the group is a female that earns between $30,000 and $39,999

A health educator wants to evaluate the effect of a dental film on the frequency with which children brush their teeth. Eight randomly chosen kids are measured on the number of times they brushed their teeth for one month before viewing the dental film and again for a month after the film.    Child  Before  After  1 23 27  2 28 29  3 22 25  4 30 30  5 26 25  6 24 28  7 25 28  8 22 24   Therefore, the research hypothesis is that the dental film is effective at changing the frequency with which children brush their teeth.     Hint: Make sure you do After-Before.       Step 1. Express the substantive question as two statistical hypotheses. H0: Answer Answer Answer   H1: Answer Answer Answer Step 2. Draw the sampling distribution under the null hypothesis using the p < .05 as the criterion for statistical significance to determine the critical values. What is the center of the distribution? Answer Answer Answer What are the critical values?…