HIM 4331 Midterm
Percentiles
For the data point x, the percentile of x is the percent of data points less than x example:a score in the 75th percentile of an exam -75% of test scores are lower than your score -25% are the same or greater than your test score.
Null and Alternate Hypothesis
H0: The null hypothesis, a statement that there is no difference Ha: The alternative hypothesis, also called the research hypothesis, is a statement about the population that is the opposite of H0 . E.g. We want to test that 42% or more of the nursing students who take the RN exam pass on the first try. Let r be the pass rate for the RN exam on the first try. H0: r < 42% Ha: r >= 42%
Ratio
Has a true zero starting point age in years height weight time pulse rate exam scores
Interval
Interval - natural order with spaced intervals income in dollars birth year time of day blood pH SAT score temperature (Celsius)
Which types of data variable(s) are evaluated with a Chi Square test?
Nominal and Ordinal
Quantiitative (Numbers)
Numbers from counting and measuring data attributes of the population. Two types: Discrete - can be counted Continuous - can have infinite number of values
Qualitative (Categorical)
Population characteristics that can be put into categories (groups) such as hair color blood type ethnicity geographic location
Stratified Random Samole
Population is divided into unique subsets or strata which are mutually exclusive (no overlapping) and exhaustive. Sample - sample from strata may be equal or assigned proportionally according to the relative size of each strata A simple random sample is then selected from each of the subsets (so only some of the subset members are selected) E.g. stratify the college students within the Biology department by major then take a proportionate sample from each major
Binary
Qualitative, a special case of nominal data Binary means the data can have two values Pass/Fail Yes/No Can code data to be binary E.g. Disease classification - patient does not have disease = 0; patient has disease = 1
Ordinal
Qualitative; has a natural order Rating scale = strongly disagree, disagree, neutral, agree, strongly agree pain rating survey ratings: "excellent," "good," "satisfactory," and "unsatisfactory" top five vacation sites
Nominal
Qualitative; no natural ordering; mutually exclusive categories blood type country favorite food zip code college major
Systematic Sampling
Select a random start then select every nth subject from the population. E.g. Select every tenth chart from the surgical department for review
Simple Random Sampling
Select randomly or by assigning numbers, each person has an equal chance of being selected. E.g. draw names out of a hat, assign numbers to survey participants then randomly pick numbers to generate a list of participants
Cluster Sampling
The population is divided into subsets much like the strata in stratified sampling. Clusters should be mutually exclusive and exhaustive Randomly select some of the cluster ****All members of each cluster are selected to be a part of the sample******
Type I Error
This results when a true null hypothesis is rejected. In the context of this scenario, we would state that we believe that the lab influences the gender outcome, when in fact it has no effect. The probability of this error occurring is denoted by the Greek letter alpha, α
A hospital inpatient was admitted on May 8 at 1 am, and he died on May 9 at 10 am. The length of stay for this patient is 1 day.
True
All states must report cases of notifiable diseases to the Center for Disease Control when they are identified by a healthcare facility.
True
Cause-specific death rates are an example of population-based statistics.
True
Infections are a major focus because they can lead to complications, longer inpatient stays, reimbursement issues, and even death.
True
It the p value is greater than or equal to the alpha value we do not reject the null hypothesis.
True
Patient A was admitted at 10 am on September 8 and discharged that same day at 4 pm. She has a LOS of one day.
True
True or False. A smaller p value provides more evidence against the null hypothesis.
True
True or False. For the chi square distribution, the standard deviation is sqrt(2 * df ).
True
True or False. If the ANOVA p value is less than alpha it means all the test results were significant.
True
True or False. If the linear regression coefficients are not zero, the independent and dependent variable are related.
True
True or False. If you draw random samples of size n, then as n increases, the sample means form a normal distribution called the sampling distribution.
True
True or False. The best Chi Square test for comparing two populations, like the population before and after a drug test, is the test of homogeneity.
True
True or False. The probability of committing a Type I error is decreased when you decrease your alpha significance level.
True
True or False. You want to test that the mean age of graduate students at your college is greater than 28 years. Thus, your null hypothesis would be that the mean age of graduate students is less than or equal to 28 years of age.
True
True or False. You would reject the null hypothesis if the F test critical value is greater than the F test value from the ANOVA test.
True
When calculating the net autopsy rate, coroner or medical examiner cases that are not autopsied by the hospital pathologist are not included.
True
Your null hypothesis is that the new medicine you are testing does not reduce systolic blood pressure. This hypothesis is actually false, but you failed to reject it. What type of error is this?
Type II
In the linear regression equation y = a + bX, which variable represents the dependent variable?
Y
You collect data on the color of cars driven by students in your statistics class, the best chart to display the data is:
bar chart
The distribution of height in centimeters for girls aged five years and no months has the distribution: X ~ N(109, 4.5). The Z-score for one girl is −0.89. This means that she is ______ the average height for girls of age five years and no months by _______ standard deviations.
below; 4.5
Your daughter brings home test scores showing that she scored in the 80th percentile in math and the 76th percentile in reading for her grade. This means that your daughter scored ________ than 80 percent of the students in her grade on math and _________than 76 percent of the students in reading.
better; better
Which is not an example of a vital statistic?
census
The manager of a department store decides to measure employee satisfaction by selecting four departments at random and conducting interviews with all the employees in those four departments. What type of survey design is this?
cluster
You want to conduct a Goodness of Fit test on whether customers have a preference among five flavors of coffee. You expect that the customers will like each coffee flavor equally. Thus, the alternate hypothesis is that
customers prefer one flavored coffee over another
Which is not an assumption for the ANOVA test?
factor is a numeric variable
Let alpha = 0.05. You conducted a Chi Square Test of Independence on the relationship of gender and post-operative infections (Yes or No). The p value was 0.06. Thus, you would ______ the null hypothesis and conclude that gender and post-operative infections ________ associated.
fail to reject, are not
The median hours to complete a 60-minute exam was 40 minutes. You finished in 30 minutes. Your time was _______ than the median indicating that you finished _____ than half of the exam takers.
faster; before
What graph is not used for categorical data?
histogram
You get data from the U.S. Census Bureau on the median household income for your city. Which chart is the better choice to group and display this data?
histogram
If the p value from your statistical test is _______than the alpha significance level the hypothesis test _________statistically significant.
less; is
Mean
measures typical (average) value; influenced by outliers
You have numeric data with several outliers, which is the best measure to reflect the average value of the data set?
median
Median
midpoint of data; less influenced by outliers
What type of measurement scale is being used when you measure blood type?
nominal
You obtained Chi square data from a sample that you collected, these frequencies are the __________ frequencies.
observed
You want to determine if the mean weight of your research group is lower after the members have been on a special low-fat diet for two weeks. Which is the best t-test for this research?
paired t-test
Imagine that the U.S. federal government had the means to survey all high school seniors in the U.S. concerning their plans for future education and employment, and found that 50 percent were planning to attend a 4-year college or university
parameter
Which is not a qualitative variable?
pulse rate
Number of visits per week is what kind of data?
quantitative-discrete
We want to test that 80% or more of the students who take the RHIA exam pass on the first attempt. Let r = the pass rate for the RHIA exam for the first try. Which is the correct alternate hypothesis?
r >= 80%
Let alpha = 0.05. Your null hypothesis is H0: mean exam score on the first test = 80. You calculated a 95% confidence interval of (70, 79). Do you reject or fail to reject the null hypothesis?
reject, because the CI does not contain the exam score 80
True or False. A study finds that the mean amount spent on produce per visit to a grocery store by the customers in the sample is $12.84. This is an example of a:
statistic
A health club is interested in knowing how many times a typical member uses the club in a week. They decide to ask every tenth customer on a specified day to complete a short survey including information about how many times they have visited the club in the past week. What kind of sampling is this?
systematic
True or False. In a normal distribution, the mean, median and mode are all equal.
true
True or False. The best Chi square test for relationships between categorical variables is the test of independence.
true
You should reject the null hypothesis if your test statistic is greater than critical value.
true
Mode
used more with categorical data; because continuous variables may not repeat.
The distribution of height in centimeters for girls aged five years and no months is: X ~ N(109, 4.5). Which is the correct formula to calculate a Z score for a height of 112 centimeters?
z = (112 - 109) / 4.5
In a biology class, the scores on the final exam were normally distributed, the mean = 85, and a standard deviation = 5. Susan got a final exam score of 95. Select the correct formula to compute her Z-score?
(95 - 85)/ 5
Let se = standard error. Which correctly represents a 95% Confidence interval?
(sample mean + 1.96se, sample mean - 1.96se)
Histogram
- Continuous numeric data. E.g. age, income Bar graph without any space between the bars Good for large datasets, e.g. > 100 values Data must be grouped before graphing E.g. ages in years could have bins: 0-25, 26-50, 51-75, 76-100
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The graphs of y = a + bx can have many different slopes. For example, when the slope equals _______ the line would slope downward.
-2
Which correlation results indicates a strong correlation with an upward slope?
0.8
The confidence level for a 95% CI is has a z value of ________.
1.96
The midterm grades on a chemistry exam, graded on a scale of 0 to 100 are below. Which grade is the outlier in this data? 64, 65, 65, 68, 70, 72,75, 75, 75, 76,78, 78, 81, 83, 84, 98, 100, 100, 120
120
Your linear regression test produced an adjusted R squared value of 0.025. This indicates that ________ of the variance of exam scores is explained by hours of study.
2.5%
We have sampled 100 customers on their preference for 5 diet soda brands. If there were no preference on diet soda brands, we would expect that ________ people would select each flavor.
20
The assumptions for the Chi Square Goodness of fit test are that the data are from a random sample, and the expected frequency for each category is ______ or greater.
5
You are given that the mean = 15 and standard deviation = 4.3. Which is the correct formula to calculate the number that is two standard deviations above the mean?
5 + (2)(4.3)
Your data is normally distributed. This implies that approximately ________ percent of your data will be above the mean.
50%
In a class of 35 students, seven students received scores in the 70-79 range. What is the relative frequency of scores in this range?
7/35
You had to wait 90 minutes in the emergency room of a hospital before you could see a doctor. You learn this wait time was in the 82nd percentile of all wait times. This means that ______ percent of patients had a shorter wait time than you, and only ______ percent had a longer wait time.
82%; 18%
A newborn born in a car in the parking lot of the hospital, and then admitted, is a hospital newborn patient.
False
A small standard error indicates the sample mean is not a good population mean estimator.
False
The gross death rate formula is the total number of IP deaths minus the deaths occurring in less than 48 hours after admission
False
The standard deviation of the sample means is equal to the population standard deviation.
False
There were 100 cases of flu diagnosed last year, and 25 new cases diagnosed this year. The 25 new cases represent the prevalence rate for this year.
False
True or False. According to the Empirical Rule, given a mean=800 and standard deviation = 150, the formula for the finding the percentage less than 600 would be (600-150)/800.
False
True or False. The ANOVA test will tell you which group means are different.
False
True or False. The alternate hypothesis for a test of homogeneity is that the distributions of the two populations are the same
False
True or False. The relative frequency of a value that occurs 10 times in 100 observations is ten.
False
Which test compares between group and within group variances to make inferences about the means of 3 or more groups?
ANOVA
Which is a continuous variable?
Amount of time students studied for a Biology quiz
Quantitative: Discrete
Can be counted. 0,1,2,3,4, etc. Whole numbers count of children living at home number of electronic devices you own number of patients admitted
Bar Chart
Categorical data Data must be grouped with frequency counts and it must be in a frequency table before you make your bar graph:
Quantitative: Continuous
Data can have any value within the range studied. May include fractions and decimals. annual income length weight time
Percentiles Examples
E.g. You scored in the 80th percentile on a national exam. There were 1,200 people who took the exam. **How many people scores at least as high as your score? *** 80% scored less than you, thus 20% scored the same or greater than your score number of people scoring at least as high = 1200 * 0.2 = 240 people
