Chapter 9 - Examining Populations and Samples in Research

Question 1

a particular group of individuals or elements to be studied (ex: patients with heart failure or intravenous catheters)

Answer 1

population

Question 2

all elements that meet the sampling criteria for inclusion in a study

Answer 2

target population

Question 3

portion of the target population to which the researcher has reasonable access

Answer 3

accessible population

Question 4

the selected group of people or elements with which to conduct a study; should represent an identified population of people

Answer 4

sample

Question 5

extending the findings from the sample under study to the larger population

Answer 5

generalization

Question 6

process of selecting a group of people, events, behaviors, or other elements that are representative of the population being studied

Answer 6

sampling

Question 7

list of the characteristics essential for membership in the target population

Answer 7

sampling criteria

Question 8

characteristics that the study participant or element must possess to be part of the target population (ex: “In this study, the sampling criteria may include adults 60 years of age or older, ability to speak and read English, and undergoing a surgical replacement of one knee joint.”)

Answer 8

inclusion sampling criteria

Question 9

characteristics that can cause a people who meets the inclusion criteria to be excluded or removed from the target population (ex: “Those patients with a history of previous joint replacement surgery, diagnosis of dementia, or diagnosed with a debilitating chronic muscle disease will be excluded.”)

Answer 9

exclusion sampling criteria

Question 10

the sample, accessible population, and target population are alike in as many ways as possible

Answer 10

representativeness

Question 11

The expected difference in values that occurs when different participants from the same sample are examined. As sample size increases, this decreases, resulting in more values closer to the mean, which improves representativeness.

Answer 11

random variation

Question 12

A consequence of selecting study participants whose measurement values differ in some specific way from those of the population. Usually expressed as a difference in the average values between the sample and population. Most of the variation from the mean is in the same direction.

Answer 12

systematic variation, or systematic bias

Question 13

each person or element in a population has an opportunity to be selected for a sample; all the subsets of a population have a chance to be represented in the sample

higher generalizability

Answer 13

probability sampling (random sampling)

Question 14

a list of every member of the population, using the sampling criteria to define eligibility

Answer 14

sampling frame

Question 15

sampling method that involves random selection of subjects from the sampling frame for a study

most commonly used for quantitative research

Answer 15

simple random sampling

Question 16

sampling method used when the researcher knows some of the variables in the population that are critical to achieving representativeness; the sample is divided into strata or groups using these identified variables

most commonly used for quantitative research

Answer 16

stratified random sampling

Question 17

sampling method in which a frame is developed that included a list of all groupings (e.g., states, cities, institutions, or organizations) that could be used in a study; a randomized sample of these states, cities, institutions, etc, can then be used in the study.

most commonly used for quantitative research

Answer 17

cluster sampling

Question 18

sampling method used when an ordered list of all members of the population is available; every __th individual from the list is selected, using a randomly selected starting point

most commonly used for quantitative research

Answer 18

systematic sampling

Question 19

sampling method in which not every element of the population has an opportunity for selection; this approach decreases a sample’s representativeness of a target population but is commonly used in nursing studies because of the limited number of patients available for research

Answer 19

nonprobability sampling (nonrandom)

Question 20

sampling method that involves including subjects in a study because they happened to be in the right place at the right time

most commonly used for quantitative research

Answer 20

convenience sampling

Question 21

convenience sampling method with an added strategy to ensure the inclusion of subjects who are likely to be underrepresented in the convenience sample, such as women, minority groups. The goal of this sampling method is to replicate the proportions of subgroups present in the target population

most commonly used for quantitative research

Answer 21

quota sampling

Question 22

sometimes referred to as judgmental or selective sampling

involves the conscious selection by the researcher of certain subjects or elements to include in a study

most commonly used for qualitative research

Answer 22

purposeful or purposive sampling

Question 23

sometimes referred to as snowball, chain, or nominated sampling

sampling method that takes advantage of social networks and the fact that friends tend to hold characteristics in common; subjects meeting sample criteria are asked to assist in locating others with similar characteristics

most commonly used for qualitative research

Answer 23

network sampling

Question 24

sampling method often used in grounded theory research to develop a selected theory through the research process

most commonly used for qualitative research

Answer 24

theoretical sampling

Question 25

number of individuals participating in the study

Answer 25

sample size

Question 26

When do questions occur about the adequacy of the sample size in quantitative studies?

Answer 26

Questions about the adequacy of the sample size occur only when no significant difference is found. If the study was designed to make comparisons and significant differences were found, the sample size was adequate.

Question 27

used to evaluate the adequacy of the sample size in quantitative studies

Answer 27

power analysis

Question 28

the ability of a study to detect differences or relationships that actually exist in the population; aka the ability to reject a null hypothesis correctly

Answer 28

power

Question 29

What is the minimum acceptable level of power for a study?

Answer 29

The minimum acceptable level of power is 0.8, or 80%. This power level results in a 20% chance of a Type II error, in which the study fails to detect existing effects (differences or relationships).

Question 30

the extent to which the null or statistical hypothesis is false or, stated another way, the strength of the expected relationship between two variables or differences between two groups

easier to detect with larger samples

Answer 30

effect size

Question 31

factors that affect what makes an adequate sample size in QUANTitative studies

Answer 31

• effect size (when effect size is large, detecting it is easier and can be done with a smaller sample)
• type of studies (quasi-experimental and experimental studies use smaller samples more often that descriptive and correlational studies)
• control (as control, reliability, and validity increase, the sample size can be decreased)
• number of variables (as the number of variables increases, the sample size may need to decrease)
• measurement sensitivity (as accuracy and precision decrease, the sample size needed to obtain significance increases)
• data analysis techniques (the power of the analysis technique increases as precision in measurement increases)

Question 32

When is the number of participants in a qualitative study adequate?

Answer 32

When the newly collected data begins to be the same as what as already been collected (saturation)

Question 33

factors that affect what makes an adequate sample size in QUALitative studies

Answer 33

• scope of the study (broad scope = needs larger sample)
• nature of the topic (difficult to define & awkward to discuss = needs larger sample)
• quality of information (high data quality = fewer participants needed)
• study design (multiple interviews are conducted with subjects = higher data quality)

Question 34

site or location used to conduct a study

based on purpose of study, accessibility of sites, and number/types of participants available in site

Answer 34

research setting

Question 35

an uncontrolled, real-life situation or environment; researcher does not manipulate or change the environment for the study (ex: participant’s home)

Answer 35

natural or field setting

Question 36

environment that is manipulated or modified in some way by the researcher

Answer 36

partially controlled setting

Question 37

an environment structured for the purpose of conducting research, reducing the influence of extraneous variables (ex: laboratories, research centers, test centers in hospitals)

Answer 37

highly controlled setting